Class D audio vs James Romeyn

 I wonder if any one was able to compare those two class D amps? I understand that they are based on different modules, but this is not necessarily the most important for the sound quality.
 I'm looking for class D amp in that price range.
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D class will never be as good as A or a well done AB or a great tube amp.
I have tube amp/very efficient speakers in my other system.
This is a different project. I have Virtue audio Sensation in this system, need more power. It's a class D and I'm not unhappy, just need more power in compact package.
After some discussion, my friend loaned me his James Romeyn Class D mono block power amplifiers and I liked them very much.  They sounded much better than my Luxman 590ax Class A integrated amplifier.  The music was more open, detailed with much improved bass.  I was very surprised and could not believe it. 

I consulted with James and decided to buy his Hypex NCore NC400 dual mono block power amplifiers with 2 NC400 amps per side with the NC1200 power supply.  He recommended his Class D dual mono version for improved sound quality.

The amplifiers finally arrived and they were a step above his mono block power amplifiers. The sound quality from my Hypex NCore NC400 Class D duel mono block power amplifiers is amazing.  

My sound system sounds much improved over my Luxman 590ax Class A integrated amplifier.  I mentioned this before in previous posts but we removed the R141 chip from the 4 NC400 amps that allow increased volume setting from my Bricasti M1 SE DAC. 

I am hearing details, imaging and bass that I have not heard before. My system now offers breath taking detail, transparency, lack of noise, and excellent dynamics that I did not hear with the Luxman 590ax Class A integrated amplifier.  

I  purchased the Hypex NCore Class D amps from James Romeyn Music and Audio, LLC (James).  He was very helpful answering my many questions and I suggest you contact him for more information on his assembled Hypex amplifiers (he offers 3 models).
how old were the tubes in the Luxman?
My Luxman 590ax integrated amplifier was solid state.  Sorry, no tubes. 


     My first class D amp was a classDaudio SDS-440-CS stereo unit I bought about 3 yrs ago.  I was very impressed with this unit that replaced a class A/B Aragon 4004 MKII.  It's very powerful (220 and 440 watts @ 8 and 4 ohms), is very affordable ($630), has an extremely low noise floor, great bass response,  excellent dynamics, has a very neutral character and has a very detailed but smooth mid-range/treble that is never harsh or bright.  This amp is also 1/3rd the size, weight and price of my former amp while never getting warmer than luke-warm no matter how hard it's driven.  Highly recommended.

     I believe the James Romeyn class D amps you mention is a kit built stereo amp based on the Hypex 400 power modules and switching power supplies.  James builds these kits in a custom case for about $1,500.  He also offers the same amps in mono-block form for a higher price.

     I have not heard this amp but, from what I've heard and read about them, the Hypex 400 kit amps are also excellent performers that have similar qualities as those I attributed to the classDaudio amp I own.

     There is another class D stereo amp that I know is very good in your price range; the D-Sonic M3-800S for $1,475. 

     The D-Sonic uses a different power module from a Scandinavian company (Anaview/Abletec) that is based on phase modulation while the 2 you are considering use pulse width modulation (PWM).  

     I own the mono-block version of this amp, M3-600-M, and can tell you this is the best amplification  I've ever used in my system.  They have the same attributes as my classDaudio amp but with more power, even better dynamics with an even smoother and sweeter mid-range and treble.  D-Sonic offers  in-home trial periods , too. 

    I'm not a dealer, just a fan of good class D amps 


Thanks to everyone for the very useful information. There is one more class D company that also offers in home trial- Digital Amplifier Company? Anyone familiar with them? 
Don't forget the NAD M22!
 emb: D class will never be as good as A or a well done AB or a great tube amp.
I understand your point of view. I use switching amplifiers yet I listen with tube amplifiers which is why I respond to statements like yours from time to time.

I grew up with vacuum tube amplification, suffered through the infancy of early solid state and realized my beloved Ayre V-1xe was aging out after years of continuos use.  I purchaced the inexpensive the PS Audio HCA-2 before its review purely as a stopgap but became enamored by its virtues which tube or linear solid state simply can't touch. I've had a switcher in the house ever since. 

Yes, most switching amplifiers have a fundamentaly different presentation. In my case a pair of originally offered Hypex nCore 400s fastened to a hunk of 6/4 Maple that drive my studio monitors with amazing clarity, transparency, and seemingly unaffected by gain (within reason). As you say it would take a "great" as in $$$ to approach this type of presentation. What my $1248. plus shipping gets me is a plate glass view into my small world of mixing.

Even though I prefer listening to my all tube analog system the Hypex design was a huge sonic leap in switching amplification which IMO has taken yet another huge step up. I just heard one of my home made files played through an Anthem pre/pro processor feeding a 200 watt ATI Class D driving some Joseph Audio floor standing speakers.

bakaolvb, read the Kalman Rubinson review in the March Stereophile. Morris Kessler's work speaks for itself. 

bakalovb I forgot to mention.

I'm essentially using what Romeyn builds sans the casework and includes a version of the Hypex switch mode power supply. The two channel 200 watt ATI AT522NC ($1895. w/seven year transferable warranty) uses a Kessler designed power supply which should be of interest.
I had never been in the room nor heard the system the ATI Class D amplifier was driving so I can't comment on the sonic differences betwee the standard nCore with a switch mode power supply to the ATI. On the other hand I would strongly suggest an audition of the ATI or trial period, if possible. The two channel ATI is only a few hundred dollars more than the current build DIY nCore 400 kit.

If you follow Class D amplifiers you'll soon learn a large portion of their performance relates directly to the AC power they're fed. I found the quality of the utilities voltage as well as the design of the dwellings wiring from the utilities main to the wall receptical made a very noticeable improvement in mt home. When I replaced my homes Romex with uninterupted dedicated 20amp 12 ga. metal clad BX my entire system benefited but the switching amplifiers are what really benefited. The ATI's power supply design may ameliorate the usuall Class D AC issues.    
Can't agree more about the power supply! My Sensation has, I think, a Doddson power supply ( not the battery) and it's a different animal with it. 
BTW, I'm using a Squeeze box duet with PS that costs 2x than SB and it sounds so good (via Anedio D2 DAC) that I'm still reluctant to change it, for example for the Bluesound Node that I have in my other system. I know, eventually I will, when MQA has more titles in Tidal.
Good, you got it. I believe this is the very area were most reviewers and people doing a casual auditions unknowingly handicap the potential performance of many switching amplifiers. 

I found another worthwhile improvement from affordable NuForce speaker cable over my Cardas Golden Ref. I had a pair of NuForce Ref SEs before the nCores. Not sure what happened to NuForce. No other reason to go to Milpitas now. 
I would like to take this opportunity to list some random notes Re. my James Romeyn Hypex Professional Build Service, specifically my Hypex NCore NC400 Stereo and Hypex NCore NC400BTL (Bridged Tied Load) high end audio power amplifiers.

I respectfully request readers allow me to open w/a singular shameless plug. Alan Silverman of Arf Productions! Studio in Brooklyn has won two Grammy Awards. Alan is one of our happy and satisfied NC400 owners, and he paid full price. I should look up Alan’s exact words via email, but suffice to say Alan typed something like, “NC400 changed the way I listen to music.” Interestingly, Alan’s first impression was puzzlement, NC400 sounding so different than anything else he heard prior, that he was not sure what to make of it. Alan might be the last person on earth to make a quick or snap judgment concerning audio performance, the polar opposite of some audiophiles. Shameless plug closed.

Since designing and releasing the Stereo chassis several years ago, regular mono blocs ceased production, not to be confused w/NC400BTL Bridged Tied Load mono bloc. Our Stereo amp has 1200W PS, exactly twice the 600W PS in the regular/discontinued mono blocs.

NC400 Stereo: $1490/ea, 200/400/600W @ 8/4/2 Ohm, 1 Ohm minimum

NC400BTL mono, same chassis as Stereo: $2980/pr, 400/800/1200W @ 8/4/2 Ohm, 1 Ohm minimum, includes free internal optional foil capacitor across speaker output per Hypex recommendation, outperforms Stereo version at all power levels, even fractions of a Watt.

I have shipped the above amplifiers to happy and satisfied clients all over the globe. NC400 works perfectly well w/50 Hz or 60 Hz AC mains voltage from 110V to 240V.

Since 2015 we installed IEC input w/Rhodium plated contacts, an audible upgrade. Owners w/the earlier nickel plated IEC can upgrade for $7 plus round trip shipping, turnaround time usually one business day. Also since 2015, we installed Hypex’ so-called nAmpon (Negative Amp On) switch on the rear panel, easily accessed in the top hole between the XLR jacks. Up = normal play/20W idle current, Down = input mute/4W idle current. Users can swap inputs in the down position.

How reliable and how bulletproof is NC400? For about thirty seconds I saw someone accidentally short the speaker outputs of his two NC400BTL (again, 1200W @ 2 Ohm, 1 Ohm minimum). One NC400BTL made a sequential “click” sound. Not only was nothing damaged, not even the PS fuse blew in either amp. I suspect most amps would have incinerated output transistors in one or both amps, and possibly even one or both PS transformers. The only error more brutal I can imagine is applying AC mains voltage to the speaker outputs. NC400 is among the most bulletproof amps extant.

Hypex designer Bruno Putzeys stated the component w/the shortest shelf life is the largest power supply capacitor. After twenty years of use, Bruno stated this capacitor may change its value but would likely still be within OEM specs.

Based on the above, let’s estimate a twenty five year shelf life for this capacitor. I estimate, in today’s dollars, replacing this capacitor out of warranty would cost about $125/25 years = $5/year service cost + AC mains voltage (very low).

No offense to competing Class D amps, but one gets the impression that Hypex shall be around for service for many years.

NC400 built today might need its PS capacitor replaced in 2042. Presumably, a similar exercise w/a typical Class A and/or Class AB amp would look less attractive.

Electrolytic power supply capacitors have two shelf life specs, “dry” (no voltage applied/not in use) and “wet” (voltage applied in use in circuit). The latter is generally about 1/3rd greater than the former, meaning the above described power supply capacitor lasts about 1/3rd longer w/AC mains current applied to NC400. I would suggest flipping the nAmpon switch up during waking hours and down during sleep time. Of course, always unplug AC mains to NC400 during electrical storm or threat of same.

Of all NC400s we built, only one client demanded RCA inputs. Bruno is adamant there is no good reason to employ RCA input instead of NC400’s fully balanced input, even w/unbalanced source. Per Bruno, the following unbalanced source applications almost match the performance of a fully balanced source:

  1. Unbalanced source RCA > quasi-balanced IC > NC400 XLR input, or close second...

  2. Unbalanced source RCA > RCA/XLR adapter > balanced XLR IC > NC400 XLR input

Avoid the following applications, for which no good reason exists to employ:

      1. Unbalanced source RCA > unbalanced RCA IC > RCA/XLR adapter > NC400 balanced input or...

      2. Unbalanced source RCA > unbalanced RCA IC > NC400 RCA input

Plug your new NC400 directly to the AC mains power, using no filtration or so-called purification device, which degrades performance.

NC400 has huge current capacity. Even @ 8.5 lbs, it supplies as much or more current than 100 lb Class AB amps. The worse/more difficult is the speaker load, the more does performance improve by lowering speaker cable series resistance. Ideally, NC400 owners should view graph depicting their speaker’s impedance and phase angle across the full bandwidth. I found NC400 to supply so much current that some applications benefit with less series resistance in the speaker cable than what is recommended in online calculator for this purpose.

OK, I lied. Shameless plug #2 and final: for decades I preferred Stan Warren’s (the S of PS Audio, P being Paul McGowan) original speaker cable recipe, which Stan personally gave me, and is equivalent 9AWG. I found cases where NC400 audio performance improved w/6AWG cables, even though online calculator recommended 9AWG. Since then I devised my own speaker cable recipe, 6AWG equivalent, that handily outperforms Stan’s original 9AWG recipe, whether the amp is an ultra low current tube OTL or ultra high current NC400 beast. Originally I sold this cable w/custom DIY solid copper terminals for only $220/pr 6 feet, but since that time I found that Rhodium terminals are indispensable, increasing the price to $320/pr 6 feet (longer lengths only moderate price increase). I unequivocally recommend auditioning these cables for any application, but especially for NC400 owners and even more so if the speaker drops below 5 Ohm, which is almost every speaker. 45-day return w/full refund in same condition as received.

The Bluesound Powernode 2 caught my eye for and wondered if it is really considered audiophile quality.  I am not trying to start any kind of war as I am ignorant on the new class D products.  Would a tube guy like myself appreciate it?  

The Bluesound Powernode 2 is a multi-room audio system that is a separate product and category than the class D power amps that bakalovb posted about. I believe it’s a higher end version of multi-room systems like Sonos. Bluesound claims it’s audiophile quality but I have no opinion since I have never used any multi-room systems. From reading about the system, I do know it’s a multiple component system based on updated bluetooth technology that’s capable of streaming high-res music files.

The only relevancy the Bluesound system has to bakalovb’s post is that one of its components contains a low powered (60 watt @ 8 ohm) Hypex class D amp. A good sign of higher quality for this system but I’d suggest you’re better served googling for reviews on this system than looking for opinions on this thread.  Or, you could always start a new thread here on Audiogon  requesting input on the Bluesound system.

Thanks Tim.  That basically what I understand too.  However, the amp portion does have outputs so I can pair it to some speakers I like.  I think they use Wifi for streaming to avoid the bluetooth limitations.

I believe the powernode 2 allows you to stream from USB, a cd player, their cd ripper etc and then had the amp section.

     I think you're right on all counts.  I don't have a need for this type of system and don't completely understand how it functions.  I think you locate  the amp, dac, computer file storage and cd ripper sections in the same room as your main speakers.  I think speakers can then be placed in other rooms in the house with signals sent via wifi but I'm uncertain if the signals are sent to powered speakers or system modules/amps that regular speakers are connected to.  I'm also curious about whether the rooms utilize a stereo pair of spkrs or just a single mono speaker.

     However, I don't think we should hi-jack bakalovb's thread so please respond and then you can seek input elsewhere or start your own thread.

Spkrplus, I apologize for comparing my shade tree assembly of a pair of nC400 kits to your impressive build.

I too heard a substantial ability to hear into my modest recordings just as your recording engineer customer compared to the linear solid state amplifiers I was using prior to the Hypex products.
That's very kind of you to mention, but I took absolutely no offense. 

For the record, there are a couple fine points Re. NC400 assembly.  On at least six occasions, clients hired me to re-wire the same subtle assembly error for NC400 built by persons not me.  The symptom of this error is NC400 works perfectly fine in one system, then moved to another system NC400 mutes, playing no music.

Again, please allow me to repeat this performance advice for all applications w/unbalanced source > NC400.  Any use of unbalanced IC unnecessarily and audibly degrades performance of this fine amplifier.  Instead, follow this IC method:
Unbalanced source > Quasi-Balanced IC (RCA/balanced cable/XLR) > NC400 XLR, or close second choice...
Unbalanced source > RCA/XLR adapter > balanced IC > NC400 XLR

The worst application, w/the greatest magnitude of AC mains noise, is the following:
Unbalanced source > RCA IC > NC400 w/RCA input and "earthed" chassis

I would like to share my experience/impression with class D amps.  I started with a Virtue Audio Sensation.  It was good but when I switched to Bel Canto S300i it was an amazing improvement in every aspect.  Just over a week ago I switched to ClassDAudio SDS-470C with upgraded power supply.  The improvement from Bel Canto is amazing.  Now I feel it is closer to good ClassAB amps.   For the remainder of my system I have a Squeezebox touch and Monitor Audio Silver 2 speakers.

You stated: " Just over a week ago I switched to ClassDAudio SDS-470C with upgraded power supply. The improvement from Bel Canto is amazing. Now I feel it is closer to good ClassAB amps."

Glad you’re enjoying your new ClassDAudio SDS-470C class D amp. I’m somewhat surprised it outperformed your Bel Canto class D integrated but I’m not surprised at all that it sounds very good; I own the model just below the 470, the SDS-440CS, and it was a similarly great performer in my system.

It has an extremely low noise floor, solid bass along with a very detailed, smooth mid-range/treble that is never too bright and with an overall neutral sound quality which is very revealing of upstream components. I found the neutrality of this amp allowed the system sound influence of my VTL preamp with NOS Mullard tubes to simply be accurately amplified, without any detectable alteration or added sonic signature of its own to the sound, which allowed it to nicely flavor my overall system sound with more texture, dimension, realism and warmth; just what I was wanting at that time.

I do have to differ, however, with your description of the sound as "being closer to good class A/B amps".

In my experience with the SDS-440 and several other class D amps I have subsequently used in my system after switching from a decent quality class A/B amp (Aragon 4004 MKII), I think the overall performance of the 3 class D amps I’ve used thus far (ClassDAudio, Emerald Physics and D-Sonic) have all significantly outperformed my former class A/B Aragon in virtually every positive amp quality; more neutral, better bass, a lower noise floor, better dynamics, more detail with similarly good sound staging and very good mid-range’treble performance.
In my opinion, many of the current good class D amps come much closer to the traditional audio amp ideal of a ’straight wire with gain’ than the recent and current good class A/B amps can muster. I have found them so neutral and revealing that I can now more easily detect the affects of system changes such as power chords, interconnect cables, speaker cables and changes in upstream components.
Due to the superior sound performance I perceive from the current good class D amps when compared to the current good class A/B amps along with class D’s additional advantages (lower price, smaller, lighter, more efficient and cooler running), I replaced all the class A/B amps in my combo music and HT system with class D amps. This switch has been completely beneficial in my system with zero negative affects that I’ve been able to detect in the past few years. I honestly cannot think of a single advantage that class A/B has over class D unless you oddly and sadly somehow misconstrue the imposing size,weight or looks of some class A/B amps as positive qualities.

I ended buying Class D audio with upgraded power supply. Had Audiosmile supertweeters and very happy with the result. Now looking to buy some relatively cheap (up to $1500 R2R DAC). Looks like Soekris will start shipping one for $1200  in early June.
Thank you everyone for the very useful info.