Merrill Audio Thor - monoblocks


Hypex-based Class D amplifiers

[Italian version]

Product name: Merrill Audio Thor Monoblock Amplifiers
Manufacturer: MERRILL AUDIO - USA
Cost: $4,500 USD (Currency conversion)

Reviewer: Todd Bromgard - TNT USA
Reviewed: March, 2015


Merrill Wettasinghe, designer of the Thor Monoblock amps, built his first crystal radio at the age of six. He describes himself as someone who was always into building electronics and other gadgets. He also studied piano and was exposed to quality home stereo brands such as McIntosh, Ortofon MC and JBL Olympus Speakers. After earning advanced degrees and a long stint at HP, he finally merged his interests and talents and dedicated himself fulltime to Merrill Audio, and the pursuit of better sound.

My first experience with Merrill Audio was T.H.E. Show 2014 in Orange County, California where I had an opportunity to hear the Merrill Audio VERITAS Monoblocks. I was favorably impressed with some of the best sound of the show: transparent, detailed and organic, despite less than ideal conditions. Learning the VERITAS incorporated Class D technology further impressed me. When I read Merrill Audio introduced less expensive mono blocks using trickle down technology from the VERITAS, I was eager to have a listen.


Like the VERITAS, the Thors utilize Hypex Modules that contain NCORE technology in the specific OEM UcD modules. Each Monoblock is housed in chassis machined from Aircraft grade aluminum block. A high level of build quality is evident upon first inspection.

The amps are small, about 9 x 9 inches, sitting side by side the pair fit on one shelf in my equipment rack. At just eight pounds each, they are light weight, but the chassis is solid and built like a tank. There are no knobs or switches visible on the exterior of the amp, just scalloped channels running down the side panel, which gives it a clean modern look. The Piano Gloss Black finish is attractive and easy to clean.

High quality parts are evident including Cardas XLR connectors, Cardas speaker binding posts, Furutech IEC and Stillpoints footers. The Monoblocks are rated at 200 watts into 8 ohms and 400 watts into 4 ohms. Despite the relatively high power rating they run cool to the touch.


Once plugged-in, the amps are always powered on, but in mute mode. To listen, press the button located on the bottom of the amp, easily accessible by reaching underneath. Once engaged indirect red light emanates from underneath, inspired by Scandinavian design. The mute button is not in the audio path, explained Merrill Wettasinghe; it simply takes voltage away from the stages, which helps keep the amp quiet. I appreciated the indirect light especially during late night listening sessions.


I found the Cardas Speaker Binding Posts to be particularly good at making a secure connection with my speaker cable, and a breath of fresh air after wrestling with less effective connectors used by other companies. The Stillpoint footers look good and seemed to have excellent isolation properties. They also provide good clearance for fingers to reach under the amp to engage the amps. The Thors run in balanced mode only, so you will need cables with XLR connectors, but it helps keep the noise floor as low as possible. As Merrill Wettasinghe explained, small incremental improvements add up to a significant improvement in audio quality.

I loved the aesthetic of the amps. The gloss black finish is luxurious and helps the amps disappear in my equipment rack. The only thing that gave them away was the indirect red glow emanating from under each amp. It's hard to believe the Thor Monoblocks are a trickle down product.

Associated equipment

I used the Thors to drive Usher Mini Diamond speakers and Magnepan Super MMG speakers with bass modules. Pre-amps consisted of the pre amp out of my Pass Labs INT 150, Parasound JC2 and a modified Jolida JD9. Source is exclusively LP record conducted via my Origin Live Resolution deck with Illustrious tone arm sporting an Ortofon Quintet Blue MC cartridge.



When I took possession of the Thor Monoblocks, I didn't have a separate pre-amp component, and used the pre-amp out section of my PASS LABS INT 150, which proved revealing. The last piece of music I listened to before making the switch was Respighi Ancient Dances, so I made it first in my music queue after the switch. The first thing that struck me was a widening and deepening of the soundstage. Instruments had greater separation, clarity and definition. The soundstage stretched further across the room, far beyond the edges of the speakers. I am a sucker for a great sound stage.

Once I secured a separate pre amp, the feeling of space increased even a little more. Sinatra Live at the Sands on the Mobile Fidelity label provided a good example of the Thors' ability to cast a wide and deep soundstage. The expanse of the venue is evident as The Count Basie Orchestra kicks into gear and Sinatra takes the stage to ask comically, “How did all of these people get in my room?” The presentation through the Thors was a little more immediate and upfront, like I moved-up a few rows into more expensive seats.

But immediacy and detail did not come at the expensive of musicality. Well recorded music always sounded natural, with nice midrange bloom and presence, never etched or harsh, even when playing loud. Stadium Arcadium by The Red Hot Chili Peppers LP mastered by Steve Hoffman and Kevin Gray sounded fantastic. The extra power delivered by the Thors really helped make the music come alive. Chad Smith's drums had plenty of impact and definition and tone, and cymbals sounded metallic but not harsh.

Tonally, the Thors are neutral and balanced with no obvious colorations I could detect. The amplification of my Pass Labs INT 150 and the Thor Monoblocks closely resembled each other in this respect. But, whether due to the added power or the monoblock design, I enjoyed listening more with the Thors engaged. The clarity and inner detail provided by the Thors helped make an emotional connection to the music. The piano present on Criss-Cross by Thelonious Monk sounds full, and after each stroke of the piano key there is a natural decay evident as each note fades into the next.

Beck's Morning Phase draws inspiration from classic California bands of the past, and encourages one to relax and be mellow. The recording is full of subtle sonic delights and makes for a great late night listening session. The Thors preserve all the inner detail and resonance that make this recording so dreamy. Once settled into the groove of this record it begs to be played again and again. The recording highlights the Thors' capabilities. A perfect black background is provided for instruments to emerge from beyond the boundaries of the speakers and swirl about the room.

The Thor's preserved details while providing power for loud passages and large dynamic swings. The Thors offered plenty of power and effortlessly drove my speakers. Dynamics were excellent, in part due to the extremely quiet Thors. In fact I could not hear any noise coming from the Thors. Their silent operation combined with their robust power allowed for dynamic swings present in music. I spun Queen's Jazz LP for the first time in years. I was a fun listen and proved a test of the amps' power, driving my speakers to maximum sound pressure levels. It is hard to image the Thors not being enough power, even those with inefficient speakers, like Magnepans.



Merrill Audio Thor Monoblock Power Ampliers are an easy recommendation. Modern aesthetics combined with powerful yet cool running Class D technology provides a musically satisfying experience with vast soundstage capabilities, wide dynamics, detail and neutral tone. The Thor Monoblocks exude quality, so much so it's hard to think of them as trickle down products. The Thor Monoblocks deserve to be at the top of your “must-audition” list.

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