Sonic Impact T-Amp - integrated amplifier

True Giant-Killer

[SI T-Amp]
[Italian version]

Product: Sonic Impact T-Amp - Class T integrated amplifier
Manufacturer: Sonic Impact Technologies - USA
List price: 39 $ (thirtynine)
Reviewer: Lucio Cadeddu - TNT Italy
Reviewed: 15 January, 2005

Dear audiophiles, what you are about to read is a very unusual review. You know us for our sincere, frank and independent approach to HiFi reviewing. In the past we reviewed many HiFi components that, for one reason or another, didn't get enough press coverage on traditional HiFi media. We drove your attention towards new products, many of these available online only, always having in mind VFM (Value For Money) and sound quality. We are proud to have had the temper and the courage to make things differently, always far from the usual mainstream HiFi hype.
Forgive me for this blatant preamble but first-time readers may need some introduction to our approach, before reading what follows.
Among many unusual reviews (here on TNT-Audio) this one will stand out, not because it is somehow "different" from our previous ones, rather because the product is DIFFERENT. It is so different than the rest that I dare to call it a real revolution. I'm talking of a sub-30$ (no typo!) integrated amplifier that embarasses the competition. Which competition, you may ask! There are no integrated amplifiers below, say, 150$!!! Indeed, the Sonic Impact T-Amp finds its natural competitors in a price range that is 100 times its price. At least. Now relax and read on.

This is NOT an April's Fool, a bad taste joke or a test to see how many of you blindly believe in what we say. No, this is the first part of a series of articles devoted to the most insane piece of equipment I've ever come across during the last 25 years of HiFi addiction. A battery-operated 6 watts per channel IC-based integrated amplifier that is so damn good sounding to cause harassment to many expensive products.

Description and tech specs

[Tripath's TA 2024 marvel]

The Sonic Impact T-Amp is a so-called Class T integrated amplifier, based on the Tripath TA 2024 chipset. As claimed by Tripath and then by Sonic Impact, the chip makes use of a kind of "Digital Power Processing". In layman's words, this is, more or less, a Class D amplifier with high rate switching properties. That is why they put the word "digital" into it. Actually, there's nothing really digital inside, not in terms of D/A conversion. You can view the official TA2024 datasheet, with detailed tech specs, power and distortion measurements at the Tripath website. The Sonic Impact T-Amp is nothing else than a pure and simple application suggested by the chipset datasheet. No magic.
Tripath makes other, more powerful chipsets, used for example by BelCanto Design for their Evo2 power amplifier (3200$) and by Audio Research on their 150.2 power amp. Also Teac makes a 3-channel power amp with the very same kind of chipset.
The TA2024 and hence the Sonic Design T-Amp delivers 6 watts on a 8 ohm load and 9 watts on a 4 ohm load. Forget the fancy and optimistic 15 watts claim since this refers to the max power on 4 ohm at a 10% distortion rate!
It can be powered by 8 1.5V AA batteries or via an external 1.2 ampere/13 Volts AC adapter (not supplied) available at 20$, only for the US market. The T-Amp has just one mini-jack line input and 2 spring clips speaker posts that barely can accept anything above 1.5-2.0 mmq. A volume knob - that works also to switch the unit on - is the only human interface supplied. No input selection (there's only one!), no tone controls, no mute, no remote. A red led lights up when the unit is on. These are the claimed tech specs:

[T-Amp rear view]

The manufacturer, Sonic Technologies, is a San Diego (USA) based Company, though production is located in China. I've tested the amplifier for a long while as if it were a standard HiFi component (which isn't), hooking up sources and speakers costing 200-300 times its price. The manufacturer's website sells it online for 39$ but the toy can be bought at other online stores for much less, even as low as 19.45$ (at Worldwide shipping may be a problem though. The only website that deals with international orders I know of is (price: 23$). This is the place where I anonimously bought the unit(s) under test.
Certain websites list it as Sonic Impact (or SI) Model 5066: it is exactly the T-Amp, not a different version.
Since this article has been firstly published on our Italian section (causing a stir!) it seems the availability at ThinkGeek may be a concern. Perhaps you can try with as well. At present day the amp seems sold-out. If you want to know why, please read on :-)
Before you think I'm out of my head you'd better browse the Internet putting "Sonic Impact T-Amp" on Google and read through the results. If I'm mad, I'm certainly NOT the only one out there.

True Giant-Killer

First things first: this toy delivers 6 watts on a classic 8 ohm load. Low efficiency loudspeakers owners beware: if your speakers have less than 90 dB/w/m and/or your listening room is large, this amplifier is not for you. Owners of >90dB speakers, small listening rooms or moderate listening level habits...please read on carefully and leave all of your prejudices at home.

This amplifier is STUNNING. And the review could stop here. Considering shipping, customs fees, VAT etc you can pay 25-30 € max for this item (non-EU Countries, make your conversions). This means the T-Amp costs more or less than a Music CD. At this price, it should deliver a multimedia-like kind of sound and shouldn't even be considered on a HiFi mag like this one. I understand you can find it hard to believe but I can assure you I found it harder, being the skeptic and investigative guy I am.

Warning: this has been the most thrilling and incredible experience I've had with a component in, say, 25 years of HiFi listening. This website has existed since 1995, I've reviewed hundreds of HiFi components, inexpensive and ridiculously overpriced ones. I never - repeat - NEVER came across such a stunning piece of gear in all of these years.

It is not easy to describe how a 20$ amplifier performs. First of all, as said, it has no competitors. The cheapest integrated amplifier I can think of costs 6-7 times the T-Amp. Trust me, it is NOT this kind of amps you should have in mind when comparing the T-Amp. In order to evaluate it you need to forget its price. Difficult? Not at all! It becomes very easy once you listen to it: tonal balance, dynamics, 3D imaging, transparency, detail...consider all these parameters critically and you'll be amazed by the results.
The tonal balance, with AA batteries, tends to be on the warm side. It shifts towards neutrality when powered with an external AC adapter. I've not tested it with external batteries so I can refer to stock alkaline AA batteries versus AC adapters (of various sizes).
I've always found the AC adapter power supply better than (fresh and new) alkaline batteries. Thus, my listening notes refer to a T-Amp powered by an external AC adapter (details on this later).

The first feeling is that the mid-high range sounds harsh and sterile. This attitude changes over time as break-in proceeds. Many suggest at least 100 hours of my opinion things get better (and interesting :-))) after a couple of days.
Harshness disappears and what you get is an extreme transparency and detail in the mid and high range. Voices, in particular, appear crystal clear and very natural. Even tiny details, such as the sound of opening lips, are revealed effortlessly.
Take for example "Dante's prayer" (Loreena McKennitt, from "The book of secrets" - WEA 0630-19404-2 - 1997). When Loreena sings "Please remember me" the P and the B are preceded by the sound of her lips, when opening to sing. The T-Amp reproduces this "sound" with a sense of presence that is simply stunning. You feel as the singer is there, right in front of you.
Overall performance on voices was the first of my main concerns. I expected a kind of harsh and metallic reproduction, considering the "target" of this product but I had to change my mind quickly. Male and female voices and even choirs do possess a realism that belongs to high class amplifications only. I'm not referring to a particular price range here, I'm talking in absolute terms. Only from time to time, especially when pushed hard to deliver all of its power, the T-Amp reveals traces of hardness and harshness.
The very same kind of transparency helps in reproducing stringed instruments such as violas, cellos, violins and guitars. Audiophiles used to the ubiquitous warmness and smoothness of low powered tube amps may initially find strings on the T-Amp too...metallic. Actually, in real world and most of the times, strings are made out of metal, rather than silk and wool :-)
What I hear through the T-Amp are extremely realistic strings, rich in harmonic content and low in harshness. And this was my second main concern: normally, inexpensive HiFi components (speakers and amplifiers, mainly) do add an unnatural coloration to stringed instruments. They make those artificial, almost electronic. You lose the harmonic content of the notes and find it difficult to detect if it's a real acoustic instrument or a synth that produces those notes.
I'm sure you are familiar with this tedious effect. Hence, I was prepared to experience the very same effect with the T-Amp. And I was wrong, for the second time in a row. Transparency, presence and realism are in top class here. Hard to believe, I know, but damn true.

The third point I was going to investigate was the bass range. If you know my listening habits you should be aware of the fact I'm a bass-freak: power, depth and control are of paramount importance to my ears. Considering the target of the T-Amp I was ready for a boom-boom kind of sound. Overinflated 100Hz and nothing else to talk about. Despite all my stupid prejudices the T-Amp delivers a tight and fast bass with excellent extension and impact. Of course, within the 6 watt limitation!
On the first track of the already cited McKennitt's album there's a big drum in the background that makes the air vibrate. I was listening to this track together with an audiophile the very first drum beats we stared in each other's eyes without saying a word. We were simply speechless. Not only the air in the listening room was vibrating but also our listening seats were. The natural decay of the big drum was so realistic that we couldn't believe to our ears. We couldn't help but laugh.

We audiophiles are used to big amplifiers with massive power supplies, heavy cabinets etc in order to make our woofers dance. Now, looking at the way the Morel woofer of these Merlin's TSM moves back and forth driven by this tiny-weenie amp is something that destroys, in a second, all our well-established HiFi faiths. I don't know how this can be possible but it's here, in front of me and I can't help but try to describe it!
And no, I'm not driven mad by the low cost of this amp. Quite the contrary!!! I'm somehow irritated by its performance. I can't tolerate my beloved references finding hard to justify their cost against this plastic toy. For this reason, I decide to try everything I can to find this amp's limits and faults. What can be better than the third track of Rage against the machine's first album? Oh well, this track is such a torture field for many amplifiers, especially if you want all the power and realism this recording can deliver. Bass and drums are simply devastating.
Well, provided you stay below clipping levels, the T-Amp gets the dirty job done: clean attacks and decays, grooving electric bass tunes glued together to form an explosive mixture. You want bass? You got it. Deep, powerful, tuneful and articulated till its deeper end.
OK, the first thing that comes to mind is that perhaps I'm affected by some kind of quickly developing aural disease. I decide to visit a friend, owner of a mid-class set-up: Rega Planet CD player, Sonus Faber Quid integrated amplifier and DIY speakers with top-class Audax and Focal drivers. The Sonus Faber Quid was/still is a very good amplifier: pacey, dynamic, extremely revealing and detailed.
Apart from the obvious power output difference (speakers are of the low efficiency kind) the T-Amp trashes the Quid, bar none. Apart from overall dynamics and impact in the bass (thanks to the extra power) everything else is done better by the T-Amp: more realistic, cleaner, more natural and with a WAY BIGGER soundstage (more on this later).
Believe me, being the owner of that amp (given to my friend on permanent loan) this head to head comparison wss deeply saddening. I didn't expect such a sad result. The beloved Sonus Faber of my early years trashed by a plastic toy. And don't think the Quid is too old to be good. It still outperforms a Puccini SE Remote amplifier of these days. I still can't believe what I've heard.

Not satisfied and deeply saddened by the results of the listening tests I decide to contact the TNT-Audio staff of reviewers worldwide, our dirty dozen. And, surprise surprise, Geoff Husband was testing the T-Amp and...guess what? he was getting the very same results. Everyone must hear or have one, he replied. If you're asking our opinion because you think you've suddenly become deaf...well, you're not deaf, my friend, this is a giant-killer. Here's his brief opinion on this little marvel.

We're a competitive lot at TNT-Audio. Often we find something interesting and sort of spring it on the others on the staff as our "find". So you can imagine my annoyance when I received an email from our illustrious editor - quote: "BUY a Sonic Impact T-Amp. At 20$ it is the most incredible thing I've ever come across in 25 years of HiFi Passion. I'd like to receive feedback from other trained ears...."
You see I'd been sitting on the same amp for a month and was just getting round to doing some serious playing with it and getting very excited in the process. Lucio's email meant he beat me to it, but it also showed something that I'd experienced myself, a certain need to check I wasn't losing the plot before going to print.
So Lucio - here's my take on the thing...

Regular readers will know that my main system is powered by am Audionote M3 pre/Quest Silver 300b SE monoblocks driving a pair of Loth-x Polaris full-range horns. Now rumours on the web had the Sonic-Impact (SI) competing with megabuck single-ended valve amps so I guess I was perfect for the comparison. The Polaris have got to be one of the most efficient, and easiest to drive speakers out there so the SI would be in it's element, never needing to draw more than a couple of watts.
So purely in the interests of research I unplugged the Audionotes, wired the Audionote Zero CD player direct into the SI via a pair of cheapo cables and a phono-jack adaptor (not even gold plated!). As the usual Sonic Link hosepipe wouldn't cram enough of its strands into the naff spring clips I used some really cruddy thin speaker cable I got with some cheap car speakers I'd bought years ago.
Switch on and of course the thing was silent, none of the hiss and hum of the valves. Putting on a bit of Steely Dan 'Aja' I sat back.
Holy s**t! For less than half the cost of one of the cheapest 300b valves this thing was making music. Huge soundstage width, detail right up there with the Audionote pairing, fast and punchy. This would seriously impress the neighbours. Obviously it'd go really loud.
This isn't my review, and I'm not going to go into great detail here, but to put this into perspective (did I really say that? A $30 amp against a $15,000 combo?) if tomorrow I invited one of you readers into my home and wired up half a dozen of the big-buck valve amps I'd had here over the last couple of years and, sight unseen, slipped in the SI as one of the test amps it wouldn't have been out of place.
But, and it's a big BUT, it doesn't sound like an SE. Crippled as it was by the worst possible cables and connectors it managed to sound hard and flat next to my own amps, I can't measure emotion, but some of it was gone. It lacked the warmth and soul and ambience that they bring to the party.
The 3-d imaging was limited but the soundstage width stunning, the detail top notch and the music relatively undamaged, it also lacked the grain of any transistor amp within 30x its price. That said I would take it over some very expensive amps I've heard, and if I was forced to "downgrade" my system by $15,000 it would be the SI that would make it bearable.
But think on - what would it do with decent cabling? What about playing with better power supplies? (the Graham Slee PSU's from his phono stages might be perfect). What about swapping a couple of components/connectors for decent stuff. What about buying two and bi-amping, or four and quad amping? What about running one as a power-amp using a high-end pre? Buy an active x-over and go mad. What about buying a really flash box, putting on some blue LED's and some chunky binding posts and sockets, a BIG volume knob and selling it for $10,000 muha, muhaha! muhahahaha argh gurgle!
But seriously folks - how's this for an idea? Buy two. Build some high efficiency boxes, maybe our TNT BFB and run "monoblocked" with one channel from each amp driving a full-range driver and the other a supertweeter? High-end for $150? I'm not going to tell you what or how to do it because at this money you can just PLAY!
Me? I've just hit Ebay for a pair of 40 year-old Goodman 401 full-rangers (12") for $50 and I have plans. After three years of disappearing up my own backside with more and more expensive equipment I feel like hi-fi is suddenly exciting again.

GO BUY ONE, then write a thankyou note to Lucio.
Geoff Husband -

Now, reassuered about the state of my ears (and mind) by Geoff's words I was ready to try everything to get the best out of this tiny marvel. First of all, a decent "oversized" power supply was necessary. Sonic Impact's AC adapter should be capable of 1.2 - 1.5 amperes max on 12 Volts but is available for 120 Volt only.
I needed something more. For a mere 30 € I've found an Italian-made stabilized AC adapter which delivers 5 amperes of current on 13.8 Volts. I wouldn't recommend to get any closer to 14 volts than that. With this power supply I can feed two or three T-Amps for passive bi-amping or tri-amping. For those who can be interested in details, the product is the ZetaGi HP 145. Other power supplies are available hence I'm not saying this is the best one can buy. It is rather inexpensive, nicely built and...powerful :-)
Powered by this AC adapter the T-Amp starts to sing seriously: power output and impact increase and, most notably, the bass range earns weight, punch and grunt. That's the way - ah ah - I like it! :-)


As said, everything is in relation with the low power output. Within its power limitations, the dynamic performance of this amplifier is impressive: perhaps not as fast and punchy as the best things out there but you'll find it hard to believe - in a blind test - this is just a 6 watts amplifier. It should be remarked, though, that ideal partners are mid-to-high sensitivity loudspeakers (say, above 92-93 dB), provided you want to listen to realistic Music levels. On the other hand, it is well know that many audiophiles, even with 88-89 dB loudspeakers, only use 5-6 watts, no more that that, during usual listenings.
Perhaps not extremely fast, the T-Amp can still pump much Life into Music, in a very natural way, effortlessly, I'd say. With high sensitivity speakers (see what Geoff writes) things can be much better than that. I'm planning further tests with higher sensitivity loudspeakers and report back (please be patient :-)).
The bass range, especially the first octave, appears slow from time to time and smoother than it should be. Even attacks and decays could be crisper. BUT!!!! I'm talking of a 23 $ amplifier. Repeat after me: 23 dollars! Music CDs can be much more expensive than that!

3D Imaging and soundstage

Oh My! Was it me who wrote good imaging is something possible with expensive amplifiers only? Shame on me. This little plastic thing reproduces a HUGE soundstage, especially in terms of width. Hard to believe, again, but the width of the stage is on a par with top class amplifications. Height and depth are still extremely good though not so excellent.
Actually this is the aspect of the overall T-Amp performance that leaves me mostly speechless. You get everything you may wish from a high-end amplifier: several, distinct virtual planes, good focus and geometrically realistic proportions. There's air, too!
The friend with the Sonus Faber Quid amp phoned me a couple of days ago saying he discovered imaging and soundstage on CDs he considered totally flat and zero-dimensional. If this is not MAGIC, please tell me how to call it. I'm still very confused.

Well, dudes, this is a first, perhaps not 100% accurate, listening test. Of course I need more time to fully understand what's happening but I wanted to share this (incredible) findings with you. I will test the T-Amp on very different situations, partners, rooms etc. I will try tweaks and any sort of thing to make it sound at its best but, even out of the box, this is a MARVEL.
Just to state things clearer: I'm not saying this is a sort of new NAD 3020. No, this is MUCH, MUCH MORE. This is an amplifier that, if paired with sensitive speakers, can make you forget the need for expensive amplification systems. I understand you are skeptic, perhaps you're thinking this is a joke or an experiment. Not so. I've even tried to limit my enthusiasm, being a "first approach" with the T-Amp. Anyway, perhaps I'm 100% mad but certainly I'm not alone. Just put "Sonic Impact T-Amp" on Google and read what other audiophiles think (I suggest the brilliant review to start with).

Some advice

[Adattatore minijack-RCA]

First of all, DO NOT judge the T-Amp with batteries or with el cheapo cables, especially the one supplied. This gem can sound MUCH better than that. Add a decent AC adapter, better if stabilized and with good current delivery (> 2A). If possible, avoid switching power supplies, in order to limit RF garbage going through the mains.
Warning: on the DC inlet there's no indication of the correct polarity: the central pin is "positive" (+).

Use your own interconnects, buy a minijack-RCA adapter like the one you can see in the pic. It costs a couple of euros and can be found at any megastore near you.
If you hate adapters you can to build your own interconnect or use the minijack-RCA cables made by Monster Cable for portables (Interlink 200 and 400). Unluckly, these cables are directional so the shielding - with the T-Amp - will be connected the wrong way. Not a real problem, the cable works, even if the shielding properties are greatly reduced.
Anyway, the best thing to do in order to fairly compare the T-Amp with your own reference amp is to use the minijack-RCA adapter with your own reference interconnects.

The T-Amp is extremely light, heavy cables can make it fall or flip upside down. Four, small drops of blue-tac will help keeping it stable. I'm trying different feet and getting very good results with the Bright Star Audio Isonodes.
Break-in and warm-up are strictly necessary. Some say 100 hours of break-in at least...I'd say even 50 hours are sufficient. Things get better slowly, though. Do not be in a hurry!
The TA2024 chipset is hyper-protected so there's no risk of burning it up with excessive heat. Anyway, try to stay far from clipping. Even excessive voltages can kill it. Max voltage should be 13.2. Mine is playing at 13.8 and is doing well. I've even tried 12V but I tend to prefer 13.8. Anyway, perhaps I've been lucky! Stay below 13.2 and you'll be home and safe.
I've tried to power it with a 19.6 switching power supply...the amp survived, despite the excessive voltage. Anyway, there's no reason to exceed specifications.
As for batteries, I've tried 8 AA alkaline batteries. Perhaps better batteries will make the amp sound better...I do not know, feel free to experiment.
One can use the t-Amp as headphone amp, with caution: first of all, there's no output jack so one has to adapt the speakers posts to a female jack. Secondly, frequency response rises at the highs as the load increases. Tripath claims the output filter should be designed to make the amp linear till 16 ohms. Hence, I'd suggest using extremely low impedance headphones or ask a techinician to modify the output filter settings. Finally, the T-Amp uses distinct L-R grounds, while headphone normally connect these together. This can destroy the T-Amp.
If you are thinking to bridge it in order to get a mono amp with more power...forget it! The T-Amp can't be bridged!

Finally, of course you can use the T-Amp to power your PC sound card but, trust me, it deserves much more than cheap PC speakers.

If you use more than one Music source (e.g. CD player, PC, tuner or turntable) you may need a preamplifier. You might wish this to be small, inexpensive and supplied with a built-in phono stage. It exists! It is the T-Preamp and it can be powered with the same power supply the T-Amp uses (12 Volts).


Before you ask, audiophile versions of this unit are already available. As an excellent and brilliant example, have a look at Vinnie Rossi's Clari-T-Amp. If you feel you just need a fancier metallic case, with standard RCA inputs and speaker posts, look no further than the T-Amp cabinet. If you want more, don't ask, just browse the Net, it is plenty of pages and discussions related to the T-Amp and Tripath-based amps.

A complete tweaking session (new box, new volume pot, new posts, connectors etc) is now available here on TNT-Audio. Tons of pics and a fool-proof step_by_step procedure, useful even for absolute beginners!


Manufacturing and finish. What do you expect I should say? It is damn cheap, anyway it is nicely built and finished. For sure it possesses one of the highest WAF (Wife Acceptance Factor) ever seen on Planet Earth :-)
The loudspeakers spring clips are flimsy and easy to break. Plus they don't accept anything else than 1.5-2.0 mmq bare wire.
As the T-Amp so small, there's not enough room between the input minijack and the DC power inlet. The volume knob isn't exactly user-friendly though extremely precise :-)

Sound. Uhm, here are my notes: output power is too low, sometimes it sounds harsh in the highs and slow in the first octave. The bass range, from time to time, lacks control, especially when pushed too hard. Overall dynamics not excellent. Now, re-read thinking at the 23$-price target. I know, I'd better keep my mouth shut :-|

Conclusions (sort of)

If you have read till now without feeling the urge of buying one, I've failed my goal :-) This is something everyone should own or test at least once in a lifetime. It helps in building a totally new perspective. I'm not saying: sell your Mark Levinson, Audio Research, Halcro or Jadis...
I'm just saying this amp is a wonder, something that can cause serious trouble even to mid class amplifications. In other words, after you listen to the T-Amp, you need to reset your "best-buy" parameters. Compared to it, many best-buys are simply meaningless. The term "best buy" itself becomes meaningless.
In case you won't like it, you can give it to a non-audiophile friend or to your son for an entry-level audiophile system.

This is a TRUE audiophile-grade amplifier, it will rock your World like no other HiFi component you've come across till now.
Please, do not take my words as gospel, buy one and listen without prejudice (if you can!). You'll agree.

We've started collecting and publishing your opinions on this amplifier. We have even published a review from a high-end turntables and tonearms designer, Carlo Morsiani.

Copyright © 2005 Lucio Cadeddu -

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