Class D Amp Journey

Lets hear your history with the black sheep :wink: of the amp world, here is mine;

My journey so far with Class D
I lost my job in 2019 and sold everything I had which was basically tube stuff Rogue, Audio Research, Modwright, started hearing about really good amps for low money, her is my history:

2009 Virtue Audio small integrated that used a Tripath chip amp later added a tube input buffer, very sweet sounding amp
2010 Audiocircle had a thread about a company out of CA ClassDaudio that hired handicapped people that built class d amp boards for kits, so I built a dual mono amp sounded great for the cost of less than 1K
2015 D Sonic M3-800 mono amps based on Pascal boards I found them a little bright and not involving
2016 Acoustic Imagery Atsah 500 mono amps with Ncore 500 boards very nice sound
2016 Nord One Up mono amps with Ncore 500 boards also heard they had custom input boards that you could change out the op-amps and customize the sound how you like it
2020 Traded Nords on the PS Audio M1200’s another nice upgrade everything is just better with tube inputs, very satisfied


First class D amp I ever heard I bought for my car stereo. Had of have been in the early 90s. Worst sounding thing I ever heard. It was out of the car and replaced in a couple weeks. Then, years later, I was auditioning my Magnepans and the dealer was using a Peachtree amp. I couldn’t get over how small it was. He said it was class D. It still wasn’t my cup of tea but way better than anything else I’d heard. When the M700s came out I was so intrigued. After all, I could audition them for 30 days. I heard them in my system and there was no going back. These were keepers. Then, PSA had to go an put out the M1200s. Again, I was intrigued. Now I own a pair. Class D is not the thing to be feared that it once was.


Other than my subwoofer’s amp, I had no experience with Class D at all until getting my M700s. For the record, they replaced an Emotiva BasX A-300 (1 year), which replaced a B&K ST-140 (33 years), which replaced a GAS Son of Ampzilla (8 years).

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My three REL Acoustics subwoofers have Class D amplifiers. That was the limit of my “experience” with such, until I recently purchased a pair of AGD Productions, “The Audion” mono. amplifiers to try for 15 days.

I am four days in and I am enjoying them so far. Very clean and effortless but more listening time is required for me to form a solid opinion.



My first class D was my Sprout100 which is in my den as my second system. With covid keeping me working from home, it gets A LOT of use. I am always startled by the subtle nuances and imaging this little guy puts out. For now, I would not give up A or A/B in my main system, but class D seems a very good option indeed.

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Classe CA-D200
PS Audio M-700’s
PS Audio M-1200’s

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First was an NAD 7050 network amplifier. Nearly 10 years ago? Ahdunno. Still use it in my workshop.

Got a Sprout100 at the end of 2018 as my foray into better audio equipment, but it didn’t really do it for me, so I sold that.

I got a Rogue Audio Sphinx V3 powering my Magnepans in my downstairs dungeon system, and it sounds great.

But because I’m crazy and I can’t leave well enough alone, I found a pair of Bel Canto M500 Ref monos to try with the Maggies and those arrive Friday.

According to the FedEx tracking, my home lobotomy kit should arrive the same day.


did you like the bel canto amps?

It took a Class A amp to pry my much loved pair of Class D amps away. If I was forced to return to them I’d survive no problem.

1980s till mid 1990s, I owned Fisher, Pioneer and Yamaha but did not have a clue what amplification bias / class was :grinning_face_with_smiling_eyes:. So, they’re excluded. The past 25 years:
Musial Fidelity F15: A (hybrid tube & MOSFEST)
Naim Nait 5i AB
Naim Uniti 2 AB (all in one)
PS Audio M700 D
Meridian Ref. 857 AB

My first Class D amp was the first commercial one ever sold, the infamous Sinclair X10 from 1965. It was actually a 2,5W amp without any output filter and radiated so much RF that it would kill radio reception in an entire apartment block. The sound was abysmal and the output transistors blew regularly. The later X20 was better, but still awful.

Skip forward 50 years and I had a Sprout100, followed by a Bluesound Powernode 2i to see if it sounded different. Both were usable neutral amps.


After a couple of Lyngdorf SDA 2175 (class D) and then a couple of Hegel H20 (class A/B), I purchased a pair of SPEC W3 power amps (class D):

These make music listening more of a pleasure than ever (sounds like tubed, but sans tubes), don’t get hot at all and drives the bass (Vienna Acoustics ‘the Kiss’) with so much detail and dynamics.

I guess these hints at what the M-1200s are like?

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yeah, I do. This basement system doesn’t get much listening time in the summer, but the Bel Cantos drive the magnepans nicely.


They say the 600M is a major improvement over the m500.

what is this, some kind of game to you?


For what it’s worth, I’m done chasing the dragon down here. It’s a nice-sounding system, and all the Bel Canto stuff was found on the used market, for a very reasonable price.

I’m still not completely convinced on the Class-D stuff… I have no bias here whatsoever, that it’s inferior to A/B or anything. If it sounds good, I couldn’t care less, and I like that they run cool.

These sound good, they really do. But sometimes with the Class-D I’ve owned, I feel something is lacking. Something doesn’t quite satisfy. Ahdunno.

Hmmmm maybe the REF600Ms are the ticket. :crazy_face:


Bel Canto got some of the best D amps out there. But from memory, they changed a couple of key components when they introduced the ref. 600s.

I bought the PS Audio HCA-2 when it was a new product and thought it was an OK amp but lacked high frequency nuance and extension so I sent it to Kyle Takenaga at Reference Audio Mods for his most extensive modifications. The workmanship for things like the circuit board standoffs and silicone dampening of components was amateurish and sloppy. Worst was the fact he’d replaced the toroid transformer mounting bolt with a plastic tie down that was cut during transport by the rough edges of the new mounting hole he’d drilled. The toroid came loose during shipping and banged against two circuit boards and chipped their corners. There wasn’t anything to be unhappy about with the with the audible results though. Pretty much all the deficiencies of the stock unit were corrected IMO. Eventually, I replaced the HCA-2 with other amps but kept it as a back up. Periodically I’d install it and was always impressed at how well it held up performance wise compared to newer amps. About the only negative I noted was an audible noise floor with average sensitivity speakers when you were within a couple of feet from the speakers.

I agree on class D… something lacking.

I’m sure the something lacking decreases as price increases but cheaper A/B to my ears is not lacking in the same way at entry level.

The MBL Noble 15 Monoblocks sounds like no other class D amp I have ever heard. They weigh a lot more than any other class D amp around. They are a great step up from my old BHK 300s and they should be at more than twice the full retail price.

They’d better sound exceptional, otherwise nobody would pay $35,200 for the pair :grinning_face_with_smiling_eyes: Also, they come with analogue toroidal transformers with protective shield which is much heavier than SMPS provided with most class D amps.

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