Has anyone tried an amp from Class D Audio?

I've been really considering getting into a Class D amp and was going to go with a homebrew Hypex build, but I ran across a post here talking about the amps from Class D Audio.

Made here in the USA and claim to sound good. Anyone have an opinion based on actual use?
Hi Tonyangel

I had a Class D Audio SDS-224 amp that was professionally built from a kit and it powered a pair of Ohm Walsh 2 speakers in a medium sized room. Sound wise the music could get loud and pretty clear. I did notice when the volume was turned down there was a little bit of buzzing or static that came from the Walsh 2s that wasn't there when I had powered them with different amps. Build quality wise the SDS-224 was very solid and pretty sturdy for what it was.

What speakers are you thinking about using the Class D Audio amps with?
I'm running a pair of Silverline Minuet Supreme Pluses.

It was my intention to put something together using Hypex modules, but then ran across the stuff from Class D Audio and it seems that what little there is about them on the net has been good.

The model I'm considering is the SDS-254. What I'm afraid of is that it's just going to sound dead. Everything being right with no soul.

What was your impression of the sound quality, other than it being loud and clear?
Hypex N-Core is the leading edge in class D, apparently.
I tried the SDS-254 and it was natural sounding and compared well with other Class D designs that I auditioned. Sound-wise it was tilted up on the low end a bit. All together I had the following in my system: Nuforce, Bel Canto, Wyred4sound, Channel Island, and Class D Audio.

To my ears, and in my system, the Nuforce bettered the Channel Islands but only slightly ... and at more than twice the cost ($2,400 vs $5,000). I am currently running CI Audio D-200's. The Class D offering was a close third. Unlike a few others, I was not very impressed with either Bel Canto or W4S. Both are ICE module based and were very detailed and clear ("Everything being right with no soul"). They were bought used and sold for about the same amount.

Finally, you can get the Class D direct from the mfg and audition in-home for at least a month. He's a good guy to deal with as well; and in terms price/performance ... you can't go wrong. Just my 2 cents.

That's the same conclusion that I came to, based on research. Still, the little company, "Class D Audio" is interesting, I think.

From what I've read, the N-Core is supposed to be a true drop in a box module that yields excellent results, as opposed to the Ice Power modules.

From what I understand, taking an Ice Power module and dropping it into a box yields results that lean way toward the cold side, requiring companies like Bel Canto to have to doctor up the input and/or output stages to get good results.

So, who's to say that this guy building his own amps (here in the U.S.) hasn't come upon a recipe that yields similar results to that of the N-Core modules?

I know that there is a large price difference, but I think that most of that is due to the exchange rate and VAT.

In any case, I am curious about these amps from Class D Audio. I'm just not curious enough to flush ~$600 down the toilet, if they are just another run of the mill class D amp. $600 can buy a heck of a nice, used Class A/B amp on the used market.

This isn't anything pressing for me. It's just something that I'm starting to give some thought to. My Aragon 2004 is getting very long in the tooth and when it goes, I just don't think it's going to be worth fixing.

Thanks for the info. What does the rest of your system consist of, in terms of pre amp, speakers and DAC?

How would you compare the SDS-254 to a mid range traditional amp, if you can make the comparison?
Just curious about class D? Have you checked out Aspen? Not class D but a world class contender.

I'm using a ClassD Audio SDS440CS amp to drive a pair of Magnepan 2.7qr spkrs. I bought it to replace my older Aragon 4004 class A/B amp that is similar to your 2004. I could not be happier with this amp. It was only $630 and puts out a solid 440 watts @4 ohms and it is very good from top to bottom. I think the CDA designer, Tom Ross, is using some proprietary design that allows this amp to handle low impedance loads. This amp doubles its power when going from 8 ohm to 4 ohm loads, which is unusual for a class D amp at such a budget price. This doubling of power, when the impedance is halved, is typically considered a good indication of a robust power supply in an amp's design.

I would recommend pairing the amp with a tube preamp if you want an organic sounding system with natural bloom and warmth. But, if you prefer a more neutral and accurate presentation, I'd use a solid-state preamp or an ARC tube preamp. From my experience, and from reviews and blogs from users I've read, the CDA amps seem to all have a neutral and accurate sound quality.

I've been using the SDS440, 60% for ht/40% 2-channel music, for the past 5-6 months and thoroughly enjoy this amp for both.

Because your Silverlines are somewhat inefficient, as my spkrs are, I would advise you to consider trying the SDS-440 or the more powerful SDS-470. I can say with confidence that you'll be able to get very good sq even at volumes louder than you'd ever care to listen without distortion, compression and without the amp getting more than merely warm to the touch.

If you decide to give one a try it won't be a big financial risk. CDA offers a 3 week trial period and you'll just be out shipping costs if you decide to return it.

Good luck and please keep us informed.

I have built and auditioned many of the Class D Audio amplifiers. They are a very neutral amp. If you want a bit of warmth in the mix, a nice tube buffer makes a work of difference. A buffer also helps putting a Class D amp in the system in regards to impedance as the Class D amps have a low iinput impedance and a buffer can have a very low output impedance.

The SDS-254 should not be a prpoblem as it has a 47K input impedance but some of the others are as low as 7K. This is also the best amp they offer in my opinion. Plenty of power, balanced inputs possible and easily handles 4 ohm loads. This module is the baseline for some hybrid amps we have designed.
A little tweaking and you really can have an exceptional piece for very litte outlay of cash.

If you are going to build your own based on one of their modules, I would recommend setting it up forst with the attenuators that come with it, measuring the resistance where it performs best for your system and then installing a resistor network in place of the attenuators (or simply leave the attenuators in for that matter. This can greatly reduce any residual noise due to the high gain of the amps.
Nobel100, it was your thread that first brought my attention to the amps from Class D Audio; especially, since you were coming from an Aragon amp similar to mine.

Response34, I THINK that neutral is what I'm looking for. I recently got my hands on a Marsh P2000 pre amp, and, as much as I liked my previous NAD C162, I think that the Marsh is in another league all together. I'm just looking for an amp that will let me enjoy the upstream components.

The reason that I'm looking at the SDS-254, rather than the more powerful model, is that the 254 is pretty close to the rated power of my Aragon and the Aragon has been all of the amp I've needed thus far. On the other hand, with the adjustable gains on the CDA amps, I may be able to make the more powerful amps work in my system and be able to rest assured that I have more than enough headroom available.

And that leads me to another point. With the Marsh and Aragon combo, I'm only able to get up to about the 11:00 position on my volume control before it's so loud that I can't think. I'm hoping that the adjustable gains will allow me to get the use of more of my volume control.

In any case, I think I'm sold. My very next purchase is going to be an amp from CDA. I just need to decide between the 254 and the 440. I know that the Minuets I'm running are small, but they are rated to 300 watts. I wonder if I've been missing something with the "little" 100 wpc Aragon.

It's also going to be nice to get that 40 something pound beast out of my little audio cabinet. I'll have room for more toys.
""Everything being right with no soul"


Are you comparing the various Class D amps apples/apples with the rest of the system all the same?

Which Bel Canto amps specifically did you have and what was rest of the system?

I have ref1000m monoblocks. I find them rock solid performance wise in every regard, which is pretty much what I expect from an amp and works for me. Whether they possess "soul" or not will be largely determined by what they are run with. Source, pre-amp speakers, ICs, all will sound different. They have high damping factor that can sound towards lean side in some setups, but sound dead on in others. I experience this myself running various speakers in various rooms off them concurrently.

I would advise you to get the more powerful SDS-440 or SDS-470 amp. The 440 ($630) is 220 watts @ 8 ohms, which is in the middle of your spkr's recommended power of 100-300 watts. The 470($695) is 300 watts @ 8 ohms, which is at the top of the range. Either of these amps, combined with your Marsh solid-state preamp, would give you an accurate and neutral quality. which is what you said you like. Your spkrs are small but somewhat inefficient at 88.5 db at 1 watt input. I think having extra power (over your Aragon's 100 watts) would result in an effortless and relaxed presentation with plenty of headroom.

Personally, this combo would probably be too neutral and accurate for my taste, but it may fit your taste quite well. If you do feel it's a bit too neutral and accurate, you might want to switch to a tube preamp.

An alternative, if it's within your budget, is the Bella Musica Ibrido hybrid amp at $1,895. I've never heard this amp but it looks very interesting. It pairs a tubed input stage with a class D amplifier which should result in a smoother presentation but the power is lower at 125 watts/channel. I believe this amp uses the ClassD Audio amp module. You can read about the amp at http://responseaudiony.com/products.htm.

I'm sorry if this adds confusion to your decision, but I just discovered this amp online tonight.

Good luck,


Thanks for the advise. I suppose that going for the more powerful amp would make sense. The main reason that I'm looking for a neutral amp is that I think I really like the sound of the Marsh Pre.

After the upgrade from my previous NAD pre, I think that I can characterize the sound of the March as not exactly tubey, but it does have tube like qualities that I've found I really like.

Although I would one day like to get into tubes, now is not the time. I do not have the space to accommodate tube equipment.

Excellent, from all you've said, I think a CDA amp is going to give you what you want. I definitely improved my system going class D instead of my old, but still quite good, Aragon amp. I think you'll also like the smaller size, weight and cooler running of the CDA amp.

Good luck and happy listening,
Mapman, not trying to get into a p---ing contest, but my system was pretty consistent at the time I auditioned various amps. Rather than read all the reviews and comments here, and then wondering if "I might be missing out on something" ... I found the only way to quell that feeling was to get 'em in for a listen. That was just the Class D amps. It took a while and there was overlap so I could do some A/B-ing. My wife really got a kick out of watching me go through my audio hobby/obsession. Now to your question re: Bel Canto - they were the M300's. As stated earlier, once I decided on the CI D-200's, they became the reference.

I went through similar comparisons to settle on digital front end ... owning/auditioning various models of CDP's and DAC's until I found a combination to settle on for a while. Same thing with speaker cables,PCs, etc. I try to focus on one element or one component at a time. Right now, I am fairly happy with things the way they are.

Sure, I may offer an opinion from time to time, but always with the caveat that it's what I like in my system and to my ears it sounds good. Would you like it? Frankly I don't know. But isn't experimentation, tuning and personalizing our own sound a big part of this hobby?
Has anyone else received their amp lately and have any comments on it?
Has anyone else received their amp lately and have any comments on it?
I have the SDS 470 driving the upper frequencies on a system biamped with Bel Canto 1000m reference on the bottom end and they sound fabulous. Speakers are SP Tech rev III, tube preamp EAR 868 .
Enthusiastically endorse the CDA as a bargain of the first order!
Thanks Springbok10 -
I've been using CI D-200s on my Timepiece 3.0s, but I'm considering trying the SDS 470 with them, and moving the CIs to a pair of ATC Passive 20s in my home studio. I've always had a "you get what you pay for" mentality, and the low price of the SDS has made me a bit hesitant. With the return policy, I guess I should just try them out and see. Have you tried out the SDS on the bottom end to see what they could do?
No, Spenceroo, I haven't. I will at some point, just want to break in the cables, etc, as I had to change cables once I bi-amped. I used to have Acoustic Zen Double Barrels, but now that I bi-amp I cant use them, so use Clear Day Double shotgun + Signal ultra, doubled up on each channel- each terminal has a banana and spade:)
Once everything is settled, I will switch the leads and will post my findings.
Hey Spencer
I think you will find the 470's quite pleasing. I have a few of the smaller powered version of these same amps and have been running them for a couple years as they are the platform of our Hybrid power amps.
Just spoke to Tom today about the 470's and will certainly be using these higher power versions as well.
Should have no problem with those Timepieces (nice to know you still have them).
Be well and keep us posted on what you decide to go with. You are welcome to contact me if you want to hear more of my thoughts on them. If you don't still have my email, you can message me through A-gon.
Hello Response34,
Knowing who you are, I feel confident with your confirmation of the 470. I'll have to give it a try. The Timepieces are just silly good. They are the centerpiece of my system, and will be with me till the end. Best audio purchase I've ever made.

I just left you a response on your other thread, asking about CDA amps from owners, and I was asking about your impressions on the CDA470. I didn't know you were going to set it up with the Bel Canto monos on the bottom and the 470 on the mids and top. I thought you'd do the opposite.

I'm glad to hear you're pleased with the results in your system but I can't say I'm surprised. I, like Spencer, am curious to know which setup sounds better once you try the CDA470 on the bottom with the Bel Cantos on top. I'm very confident that almost any system would benefit from the use of CDA amps. I want to also make it clear that I have no asociation with CDA; I'm just a satisfied customer and big fan of Tom Ross's excellent products. I'd like to one day know how he makes such good amps for so little money and the details of his proprietary technology.