Found good & affordable amp for Magnepans

This isn't a formal review, just a promised followup to an earlier thread I posted about trying to find an affordable replacement amp for my broken Aragon 4004 amp to drive my Magnepan 2.7QR spkrs. For those who don't have the time or the inclination to read this entire thread, I'll identify the name of this affordable and excellent amp at the beginning: Class D Audio SDS-440CS that lists for $660 and has a 3 week in home trial period. For those who'd like the rambling details of my experiences with this amazing amp, please read on.

My Aragon 4004 class A/B amp recently broke down after many years of great service. The estimate to repair/replace the leaking capacitors in the power supply section was $300-400. The powereful Aragon(400 @ 4 ohms) worked great with my older Magnepan 2.7QR speakers since they're relatively inefficient (87db) and need a lot of power to sound their best. So, since this amp was going on 23 yrs old (who knows what was going to go next), I decided to just buy a high powered amp to replace it on the used market.

I searched EBay, Craig'sLlist, Audiogon and other internet sites. I found out that used Aragon 4004s, even the less ancient MKIIs were going for about the same price that I paid for mine used 10 yrs earlier, around $1,000. This was more than I wanted to spend, so I changed stategies and found out, through the forums on Audio Circle and Audiogon, that a lot of people were switching to the new class D amps to drive the notoriously power hungry Magnepan speakers; this is true of owners of the small entry level MMG's through even owners of the top of the line and largest 20 series models.

I made an offer on Ebay to buy a used Wyred4 Sound class D amp, which was one of the first amps the company produced, that didn't meet his reserve price. The seller emailed me back stating it was sold but suggested I check out the new ClassD Audio completed amps. CDA began by supplying class D amp modules and related components to DIYers but has recently branched out by selling completed amps from their facility in Southern California.
I checked out their website and called them the next day. Tom Ross, the company'sowner and amp designer, answered the phone (must've been a busy phone day). He's a great guy;very knowlegable and interesting to talk to. He said he's not looking to get rich but just trying to make the best amps he can at an affordable price so he can build his small business. He told me he's currently relying on positive word of mouth, rather than expensive advertising, to help keep his products affordable.
He says he designs his amps to have the solid and well controlled bass characteristics of good solid state amps combined with the smooth, liquid midrange and treble of good tube amps. This exactly matched my tastes. After he asked me some questions about my system, he recommended either the 440 or 470 amp since either would be a good match with my system components. I chose the SDS-440 because it had about the same power as my old amp (440 watts@4 ohms) and was a little less expensive than the 470. When I opted for the brushed aluminum faceplate, rather then the black, he asked whether I'd like black screws on that or the new silver ones. I took the silver and he said, if I change my mind later, he would send me the black ones free of charge. He also said the fully balanced XLR circuit in the 440 is one of the best on the market and he would include 2 RCA to XLR adapters so I could take advantage of this (how's that for customer service?). The amp was ordered at the end of January and arrived, well wrapped and double boxed, on February 12th.I apologize for the long winded lead in but I thought it might be useful to some readers.

Before I get to how it sounds, I should tell you that this amp is quite a bit smaller and lighter than my old Aragon (about 1/3rd the size and weight). However, it is well built and doesn't look cheap in any way. It was a breeze to setup once I removed the 65lb Aragon from my rack.

Now for the important part: How did it sound?:

I'm not going to pull any punches and will relate my impressions as honestly as I can. For the first few days of listening, I was a little disappointed with the sound; it was a little too neutral and lean for my tastes. I always thought I preferred an amp to sound a touch to the warm side of neutral, without sacrificing details. I left the amp on since I wanted it to break in and it draws so little power while idling.
I called CDA on the 3rd day and related my impressions to Tom. He said his amps don't have any parts that really need to "break-in". But he said he's noticed that many people's ears/brains need time to break-in, especially if they're listening to class D for the first time. I thought that sounded a little unusual so I asked if it was OK to just return it and get my money back. He said: "no problem. You have a 21 day trial period, so just send it back with a copy of the original invoice and we'll give you a full refund, less shipping costs.". Then Tom suggested I keep it longer into the trial period to give the amp a thorough tryout and to see if I needed to adjust to the class D sound. He said I could return it at any time up to the 21 day limit. Since I only had the amp for 2 days, I agreed. As I hung up, I remembered that my preamp (VTL 2.5 with NOS Mullards) had been turned off for several days. I had disconnected the ics and shut it down when I brought my Aragon in for a repair estimate a few days earlier. I only turned it back on when I finished hooking it up to the new CDA amp. It wasn't even warmed up when I first listened to it. This could explain the lean presentation, woops.

So, since everyone is finally done laughing at my stupdidity, I'll continue. Now I had to give this amp another good audition since the preamp had now had plenty of time to warm up. I have always left my preamp and amp on 24/7 so there's normally no warm up time needed.

To give this amp a fair trial I pulled the 2.7s out about 5 feet from the front wall, past the front of my tv, to my normal 2-channel listening position. My listening position is about 15-16 ft away from the slightly toed-in speakers, which are 8-9 ft apart, with the left speaker 2 ft from the left wall and the right speaker at a roughly right angle to the open pass-thru to our dining room( no true first reflection point on the right wall due to the lack of a wall). Ocassionally,I move my chair forward a few feet to attain more soundstage depth on good recordings. The room is carpeted, with soft leather surfaced seating spread about(chairs and a couch). I have yet to convince my wife about the benefits and beauty of well placed diffusors,acoustic panels and other room treatments. I don't push it since she humors me by allowing me to turn our living room into a combination listening room/home theater. You can check out my room setup by clicking on the 'system' label below ( the pictures show the spkrs placed in their ht position, I just pull them another 3 ft further out from the wall for 2 channel listening).

As far as ht performance, this amp has been great since it was setup. Movies and tv sound excellent in DTS and Dolby 5.1. I relegated the one remaing good channel on my old Aragon to driving my passive subwoofer. The 440 is driving only the front L+R channels but does so flawlessly. I run the 2.7's full range for ht(set to large on prepro)and set the high pass filter on my sub to around 45hz(and leave ithere for 2 channel,too). The amp drives these spkrs well with great ambiant and detailed sound with surprisingly good bass from spkrs only rated down to 34hz.This amp is an excellent choice for ht.
As far as music, I had a revelatory experience on my 2nd extended listening session, after a few days of use (break-in?). This was on a Thursday night at about 11pm, a few days after delivery. I had just switched from Comcast to Directv the day before and they now offer Pandora free. I just signed up with Pandora that day and thought I'd listen to a few songs on Pandora before heading to bed. I know Pandora's not the best source in terms of fidelity but it gives me near cd quality without having to deal with changing cds.
I created a station,"Jack Johnson", because I'm very familiar with how many of his songs sounded on my old amp and thought it was a good reference test for the CDA amp. I switched the processor, being fed a Pandora wifi internet digital signal from a small 'client' server box via a digital coax cable, to 'stereo'. The processor then sends analog signals via RCA cables to my VTL preamp prior to the signals being passed to the CDA amp and finally to my speakers. Effectively, I'm using my Parasound AVC2500 preamp/processor as a Dac with analog output.
I know this is kind of a 'Rube Goldburg setup but it's just a temporary solution to get the Pandora signal playing on my system, until I come up with a better method. Anyway, the first song was "Staple it together" by Jack Johnson. The music emerged from complete silence and sounded unbeleivably good, bass was solid,, taut and textured. The best bass I can remember hearing from this often played well recorded song on my system. although there was a slight lower bass overemphasis. I think this was due to the 440's extremely high damping factor controlling the 2.7's woofer section much better than my old Aragon was ever able to. I remedied this by turning down the high pass filter crossover setting on my subwoofer to about 35hz from the 45hz setting I used with the Aragon. The midrange was a touch on the warm side of neutral and the highs were sweet and crystaline clear. The highs did not seemed to be rolled off at all. The soundstage was wide, deep and band members were clearly positioned in this acoustical space. The listening perspective was like I was sitting in the center about 15 -20 feet away from the performers. Now this was the type of system sound I was striving for ever since I got hooked on this crazy hobby/obsession 30+ yrs ago.
Pandora played song after song mixing in various artists with the ocassional Jack Johnson songs, mainly acoustic small group music. What was unusual, besides every song sounding incredibly real and like I was in the room, is that the perspective was consistently about the same for each recording:like sitting in an empty studio/nightclub in the middle and about 20 ft back from the performers. Personally, I like this non-forward presentation because it gives a very vivid sense of depth to the soundstage. But, how and why do all these various artists, at different studios/venues, recorded by different labels and by different recording engineers give such a consistent perspective on the music? One explanation might be that all the recording engineers were taught to mike these smaller groups with similar numbers of mikes in the same general locations. This is just a guess but it should be easy to check out by just seeing if I get a different perspective on larger ensemble recordings.
Anyway, every song I heard was so involving and fun to listen to that before I knew it it was 4am. So, of course, I couldn't resist playing 1 last song before heading to bed. Fittingly, the song was "Mr Jones" by the Counting Crows. It sounded the best I've ever heard this song sound, atleast in my system. Near the end of the song, the lead singer sings: "I'm just about as happy as I can be". This sums up my feelings about this excellent amp right now.
It was a dramatic sound turnaround; from 'too lean sounding' the first few days to the most incredible $660 amp in the known universe a few days later.

- Was it a magical, temporary alignment of cosmic forces? I don't think so because it has sounded just as amazing every day since.
- Was Tom wrong and his amp does need a few days to break-in?
- Was Tom right and my virgin class D ears and brain needed some time to adjust to such a different, distortion free,noise free, clean and natural musical presentation?

Given that Tom knows his amps so well, and how accurately he described how this amp would sound in my system after my 'ears burned-in': good solid state bass combined with a smooth midrange and treble that are also very detailed and revealing at the same time, I'm going to give the benefit of the doubt to Tom. However, I also think this amp benefits greatly from being paire with a tube preamp, especially if it's a fairly good one and is properly warmed up. My general thinking is that the SDS-440 sounds like nothing, it just very faithfully amplifies whateveris inputted to it. Like the proverbial 'straight wire with gain'. I'm not saying this amp only sounds good with a tubed preamp, just that I think a ss pre would likely be too neutral and lean for my tastes. You may call this coloring the sound, or a 'bandaid approach', but I don't give a f#@ck because this combo sounds organic,beautiful and just like music should to me. I'm just about as happy as I can be with this amp. Do you think the Counting Crows' lead singer was singing about his new Class D Audio SDS440CS amp? I am so glad that Tom had the wisdom and experience to know I just needed some time to adjust. After thinking about the sound of this amplifier and my adjustment to it's presentation, I've come to the conclusion that this amp comes very close to the audiophile ideal of " a straight wire with gain". It has no sound, in other words; it just takes whatever is inputted to it, amplifies it with minimal noise, distortion and coloration and passes the amplified product to the speakers no matter their impedance. If you want colorations in your amp, this may not be the amp for you.

Disclaimer: I have no affiliations with CDA or it's owner, Tom Ross. I'm just a very satisfied customer and fan of this newer company and thought fellow Audiogon members might be interested. The only professional review of the SDS-440CS I could find was printed in Stereo Times and the reviewer stated it was very similar sonically to his father's Wyred4 Sound ST-250 at 2/3rds the price.

High-End Audio is all about synergy. Glad you found an amp that works well for you in your system.
nice thread. happy you are loving your part? as I recall, you did ask one question especially the ubiquitous (take the wind of your sail question)what do you think? or How can I approve? good for you...Have a ball
i appreciate follow-up threads like this one. Very nice write up. Glad to hear you found an amp to your liking.
Thanks for the encouraging responses, you guys.

Correction: I just realized I made a mistake in my post on the price of the CDA SDS-440CS. I stated it as $660, but it's actually only $630.

Helpful and thorough review. Thanks. Just for the record, Pandora (the free version) is 128 kbps, roughly 10% of the bit depth of CDs. IMHO, the similarities you heard across different recordings could come from your source gear or your speakers. That's not necessarily a bad thing, but I highly doubt that a bunch of recording engineers have agreed on standard microphone placement. That's hifi sci-fi talk!
I did upgrade my Pandora to 'Pandora One' for about $4/month. This increases the streaming audio to 192 kbps. I did notice an improvement in fidelity which I can best describe as "CD like performance". Point well taken on standardized mic placements by recording engineers. Your explanation is much more likely but I am enjoying the presentation.
Thanks for taking the time to write such review/impressions, its incredible how you can find hidden treasures if you look patiently.
Happy listening!
Nice write up, a tube preamp in front of class D amps = great sound.
I switched years ago from the respected Aragon 8008BB to Class D Nuforce V3SE and have never looked back Congradulations on your discovery.
"He says he designs his amps to have the solid and well controlled bass characteristics of good solid state amps combined with the smooth, liquid midrange and treble of good tube amps."

Yeah, they ALL say that....

You're probably right, many class D makers do describe their amps as having ss bass with tube midrange and treble. But Tom at CDA knew I had a tube preamp. He described the sound I should expect in combination with my existing components very well. They're not lying if it's true, taking your other components into consideration. But, as Rx8man stated "tube preamp in front of class D amps= great sound". Amen, brother. But ss preamp in front of class D amp= I'm not sure, since I never heard it, but my guess would be neutral and accurate sound.

I think, in my limited experience with class D amps, that their overall sound is non existent. They will reflect whatever is inputted into it without coloration, just as a good amp should. If you like that sound, just pair it with with a neutral and accurate preamp and sources and you're all set. If you like a little more warmth and body, use some tubes in the preamp or sources. Simple, which is unusual for high-end audio.

I know I am much more confident that I could detect subtle changes in sound of various power cords, speaker cables and ic sustitutions with this amp than I ever was with my Aragon. Class D has too many advantages not to be the wave of the future. It's affordable, accurate, efficiently powerful, low impedance capable and green, to boot.

Class D amps utilizing Hypex modules will probably be the next step in this transition away from classA, A/B, hybrid and possibly tube amps.
I agree with Rxman that an excellent tubed pre such as his TRL Dude and the correct Class D is heavenly. I use an Ayon CD5s in front of mine with great results. Hpex modules can sound good but power supply, vibration control, electronic isolation, and mass loading are also important. Don't count out other designs. Many besides Hypex are rapidly evolving in the class D area.

I just checked out your system and it looks really nice. It's simple but has excellent, well chosen components. It must be a real treat to listen to music in that beautiful room and setting. It sounds like Rxman (the pharmicist?), you and I all arrived at combining tubes with class D amplification on our own separate musical quests.

I've read about the importance of class D modules (including Hypex modules) needing isolation from vibration. I notice you have some vibration control under your Nuforce amps. Can you tell me what these are and if they're effective? I'd like to address this next since my amp is sitting on a vibration prone glass rack. I'm only using the stock footers right now for vibration control. Do you use anything to isolate your Ayon?

After reading your excellent review, I was curious enough to check out Class D Audio. Their website is amazingly bad--subliterate and almost bereft of specs, info, etc.--it's almost unfathomable that they're an American company. It may very well be that they're quality people making quality products, but they'd be well-served to hire a college kid (or at least someone with a GED) to help 'em with their presentation.

Agree with you completely, their website needs some serious help. Nowadays, websites are too important not to get right. It's the public face of your company. If not professionally redone, local colleges might be a good option.
I have the Maggie on wall(4)and centre speaker in a separate HT system.
I get very good results using an Emotiva 5 channel amp that was around $350.00 new.
Granted this is HT,but I can't fault the amp's sonics nor find any noise,tech issues with it.
It's a good match for the small Maggies, and who knows maybe a bargain when using Maggies that need bi-amping.
I actually was considering the Emotiva 3-channel class A/B amp that was recently on sale for $499 on Amazon. I was going to use it to power my front L-C-R Magnepans. I didn't go this route for a few reasons:

1. The XPA-3 puts out 200 watts/ch@8 ohms and 300 watts@4 ohms. I was concerned that the amp's power supply lacked the robustness required for an amp to double wattage from an 8 to a 4 ohm load. Sacrifices may have been made to the power supply to save costs. My old Aragon 4004 put out 400 watts @ 4 ohms and the CDA that I bought puts out 220 watts@8 and doubles to 440 watts @4 ohms.

2. The Aragon amp I was replacing drove my inefficient (87db/1 watt) and low impedance (4 ohm) spkrs effortlessly with no signs of struggling. The Emotiva's 300 watts probably would have been sufficient but I was a little concerned with its ability to sound effortless and still have enough headroom.

3. The Emotiva and Aragon are both class A/B amps and I reasoned they'd probably sound similar. The class D amp, however, is a much newer topology and I thought I had a much better chance of upgrading performance through introducing a newer technology to my system than staying with the class A/B amps. Also, I had read so many great reviews and forum threads on the benefits and sound quality of class D, that I was very anxious to try it.

After having this amp in my system for about 3 weeks, I am amazed that CDA can offer this much performance for so little money. It has completely exceeded my already high expectations. I'm glad you're pleased with your Emotiva,too.

System Update in regards to the similarity in soundstage perspective, even with different recordings and artists, that I had noticed in my original post on this thread:

I replaced the 4 tubes in my preamp with fresh NOS Mullards a couple weeks ago and this seems to have solved this issue. Each recording now has a unique soundstage perspective and my system sounds even better than I originally reported.
My former set of 4 Mullards were left on 24/7 and lasted almost 6 years. Hopefully, this new set will last as long. I now know that sound stage perspective is affected by weakening tube strength levels.The perspective seems to be further away as the tubes weaken.

It was a real pleasure to read such a positive thread with minimal if no carping or cynicism. Thanks, Noble 100! I too have a tube preamp and D-class amp - EAR 868 and Bel Canto 1000M monos and couldn't be happier with the sound.
Do you think I could biamp my SP Tech Revs with the SDS 470 and Bel Cantos?
Hi Springbok,

I have a theory on why so many people enjoy running tube preamps with class D amps. In general, class D amps are very neutral and add nothing to the sound; like the ideal of a straight wire with gain. This allows the tube sound qualities of the preamp to be passed on to the speakers without any hindrance from the amp. The better the preamp the better the sound.

This quality also lets you tune your system to your preference: if you want accurate and neutral, you can use a neutral and accurate preamp ( ss or ARC tubed) and, if you want a touch of warmth and bloom, just insert a tube preamp with a more traditional tube flavor (I know my VTL with nos Mullards gives me this and I think your EAR 868 probably does the same).

Biamping your spkrs using the ClassD Audio SDS 470 and your Bel Cantos 1000Ms might work out very well. I'd call ClassD and see if they'd recommend a single 470 or a pair as monoblocks. I do know, using my less powerful SDS 440, I have never heard an amp drive my Magnepan bass panels so well (with my sub temprarily turned off).

You could also experiment with the Bel Cantos on top and ClassD on the bottom and vice versa. The ClassD are very good amps but I'm not inferring that they're as good as your Bel Cantos. I have not heard the Bel Cantos but have read very good reviews and posts on them. I think ClassD still offers a 21 day trial period, although you'd pay for the return shipping to southern California.

Good luck and let us know if you try this.

My experience with Class D Bel Canto ref1000m amps is very consistent with Noble's theory.
Thank you for your insight, Noble 100. Your explanation is very plausible and makes great sense. My 470 is arriving Saturday and I will certainly give you a follow-up.
Spring, I'd be interested to hear if bi-amping turns out to be worth it. Ref1000ms seem to have the headroom needed to drive most any speaker most effectively alone, but maybe bi-amping with them is even better somehow.
"Was it a magical, temporary alignment of cosmic forces? I don't think so because it has sounded just as amazing every day since.
- Was Tom wrong and his amp does need a few days to break-in?
- Was Tom right and my virgin class D ears and brain needed some time to adjust to such a different, distortion free,noise free, clean and natural musical presentation?"

Tom was right-on.

My experience at first with Bel Canto ref1000m Class Ds was exactly like yours with your Class Ds. My "virgin Class D" ears had to break in for sure in that the sound was so totally different than prior just as you describe.

I use an arc sp16 tube pre-amp with mine.

I did get my BCs used so they may have had some time on them already when I first heard, but I do not notice that they necessarily need any warm up time from cold start to sound great.
I'll let you know, Mapman. I, too, am dubious that it will be significantly better, but the price of the CDA makes it a worthwhile experiment. Buying another BC 1000M is another thing, altogether! Also, the SP Tech Revs are very power hungry.......................:)

Just curious if you were able to talk to Tom Ross at CDA before you decided to buy the SDS-470? Did you buy 1 or did you go for monoblocks? I don't think you'll be dissappointed with your choice either way and I'm looking forward to your impressions. I'm dubious, too, on whether the biamping will be a significant improvement but you never know if you don't try. Worst case, you return it or you keep it as a very nice backup amp.

Like Mapman, I don't think class D needs much time to sound good from a cold start, I just leave mine on for convenience since it consumes so little power.

Good luck, Springbok, I admire your sense of adventure. I always want to try out other class D amps in my system but never have.
I spoke to Tom and we agreed that it woul be better to start off with one amp. He, of course believe its better than the Bel Canto:)
I'm expecting it on Saturday.
Will keep you posted.
Where are you located, Tim?

I'm located in Indiana, just north of Indy. How about you?

Connecticut. I thought if you were in the NE you could compare the BC and The CDA.

Would've loved to. Thanks for the offer. I'll pm you if I'm going to be in your neighborhood and I'll keep a look out for your impressions.

Any luck with that new amp yet?

Did you get the CDA 470 yet? If so, how'd you set it up with the Bel Canto mono amps and what are your impressions thus far? If you need more listening time, just let us know. Hope you're pleased.

So whatever happened to the Aragon amp? Still using it as a one channel amp?
Sorry, just read this and saw I owed you a response.

I was using the Aragon's one remaining good channel (200 watts@8 ohms) to drive my passive subwoofer. But I used the unused channel on my 100 watt center channel amp to drive the sub and I couldn't hear any degradation in sound. So, I just sold the amp locally on Craig's list for $50. I bought it used for $1,000 around 1992 and that big beast gave me great sound for almost 11 yrs. Sorry if you were interested in buying it.

You actually leave your tube preamp on 24/7? How long do the tubes last?

I stated on an earlier post on this thread that my tubes lasted 6 yrs being on 24/7. But your question made me rethink this. I bought my VTL 2.5 preamp in April of 2006 and replaced the 4 stock Soviet tubes right away with 4 NOS Mullards. Then, in April of 2013, I noticed the sounstage was changing so I replaced them with a new set.
So, to answer your question, the tubes actually lasted 7 yrs being on 24/7. I never tried turning the preamp on and off daily so I have no experience concerning whether leaving them on constantly prolonged their life or not. I knew, from reading forums that many have verified that leaving the tubes on constantly does prolong their tube life. The theory is based on the idea that the tubes experience more wear during powering up and down. Leaving the preamp on avoids this and keeps the tubes at a constant voltage. I think this theory has some merit and I'm very pleased with 7 yrs between retubings.

Hey Tim,

I was going to offer to repair it for you if you were sure the caps were bad. I live in Brownsburg. Probably should check Craig's list more often, but I have never seen anything audio related worth buying locally.
Anybody but me ever see a tube unit burst into flame?
Would be un-cool to be away if that came to pass.

I've never seen a tube unit burst into flames but my experience with tubes is limited to tubed preamps. I never had a tubed power amp but I would think they are more apt to do this but don't know for certain.


Hi neighbor. Very nice of you to offer the repair but in a way I'm kind of glad my old amp broke down since it caused me to try the CAD amp as a replacement. I love this amp and doubt I would have tried it if I had the Aragon recapped.
I'm only about 15 minutes away from you. I looked at your system and would love to hear it sometime. If you're ever visiting Noblesville, feel free to stop over if you'd like to listen to my little class D amp driving my magnepans. I'll send you a PM with my phone number.