Expanding the Class D Conversation: How Would You Characterize Their Differences?

I have been listening to the Class D GanFet 6.5 stereo amp for about 24 hours now and I might as well make a comment on this since my system changes tomorrow.

GaN FET Amp: Premium 6.5 Class D Audio Review

With the great imersiv D-1 DAC the 6.5 amp sounds a little lifeless. This is surprising because with the CODA #11 and CODA #16, mostly Class A amps, the imersiv D-1 is super lively with the ultimate in resolution. With the 6.5 amp that magic is not there. I would have said this amp is no good if that is all I heard.

The other DAC that I am listening to is the Meitner MA3i on demo from my friend. What a change in sound from the imersiv D-1. The MA3i has great synergy with the 6.5 amp. It is lively with a juicy Class A like sound. The difference in sound and engagement is really surprising.

I think the CODA #16 on this system, my office Magnepan Mini system, is a bit better. It hits harder and has a bit more of a thicker Class A sound. The CODA #16 and the Meiter MA3i and imersiv D-1 are spectacular. The thing is the 6.5 and the Metner are not far behind. The 6.5 costs $1k and the CODA #16 costs $16k. My speakers in the office cost $2k. 

I have to return the Meitner MA3i tomorrow, but I am going to buy it soon. I already sold $5.5k of gear (unused Audience FrontRow speaker cable | Schiit Byggy DAC | extra Sonore OpticalRendu streamer) to make the Mietner purchase happen. I think I am going to keep the CODA #11 over the #16 since the #11 has a bit of a warmer sound and is spectacular with the imersiv D-1 on my Livingroom speaker, the Yamaha NS5000.  The #16 is great too but it is a cleaner sounding amp, and I like the warmer #11 with my super resolving imersiv D-1 DAC.

I do not think the 6.5 will be as good on the Yamaha as the #11. However, I cannot give it a good test because I am returning the Meitner MA3i. No point pairing it with the imersiv D-1 on the Yamaha.

The 6.5 definitely does not have glare. If it did, I would get ear fatigue immediately. The bass is amongst the very best I have had, such as the CODA #16, #11, #8, Krell DUO 175XD, Schiit Wotan. Not saying the 6.5 is better in the bass than any of them, but it is close enough. The #16, #11, and the Wotan are tops here

The soundstage is large and goes outside the speakers, but the Maggies make that easy to do. The depth of the stage seems a bit less than the CODA #16 (do not care for my office setup). The sound is very clean and seems like a slightly less warm Class A amp. Likely why I like it so much with the warmer Meitner and not so much with the highly resolving imersiv D-1.

Anyways, this amp is going to be my new office amp, and the CODA #16 looks like it will go to make way for the great Meitner MA3i DAC. If I had the cash, I keep the #16 and buy the Meitner. However, I made a goal of not spending new money on audio. Got to sell my existing gear if I want new gear. The 6.5 really helps me in this regard and I am loving the sound. If the CODA #16 is a 10/10 on my office setup the 6.5 is 8.5/10. That is a reflection more on the CODA and not a negative on the 6.5.

My Maggies are small speakers and need to only fill a small space. Not sure how the 6.5 would do in a bigger space. I know the CODA #16 can play small and large with the very best amps.

I am getting the #11 back from CODA after a refresh in a week or 2. I will do a head-2-head with the #16 to see which to keep.

I wish I had the Schiit Wotan amp in the house to compare with the 6.5. I thought that was a fine amp. I do know that it was not as good as the CODA #11 and #16. If I remember correctly the bass was stronger on the Wotan than the 6.5 but the 6.5 sounds a bit more Class A and cleaner.

Next week I will listen to the 6.5 in my office with the Schiit Valhalla 3 OTL/OCL preamp ($500) tuners, and RME DAC. I briefly listened to the similar Allnic HPA 15000 OTL/OCL as a preamp ($15k) on the Maggies and the 6.5. That was really good though I am also returning the Allnic tomorrow after my demo.

I should add that the 6.5 worked nicely when either an RCA source, the Valhalla 3, or the Miethner DAC (XLR) played. No toggle needed between RCA and XLR.

I had two SMSL PA200s in dual mono mode a month ago. They were very harsh,  with limited soundstage, I returned them.

Class D was preferred because of Efficiency and cost. If Class D costs as much as other class amp dump the class D in first place. Debate is not needed.  

I have had a LOT of class D and other high efficiency amps and have found that if you chose carefully, you can go back to the mid 90s and find good sounding gear.  

I am currently running what is probably the ultimate Class D, the Linn Klimax 800 but have owned or spent time (taken on trade) older Linn Chakra amps, Rogue, NAD, Primare, AVM, Atmasphere, AGD, Classe, Jeff Rowland, Lyngdorf, Peachtree, Sunfire and I am sure there are others I am not thinking of.  I have also heard Merrill amps in a stunningly good system and would call out a unique class A design that runs relatively cool from Westminster.  

My experience with Hypex/NCore has been positive but in two of the three cases there was a tube stage in front of the module (Rogue & AVM 5.2 Integrated).  These have a reputation for being a hair edgy but a solid tube stage in front takes the edge off and adds 2nd order harmonics that make these phenomenal amps.  The AVM 5.2 level integrated was what I used for a long time as my reference and before I started Verdant, the Rogue Hydra was the power amp I chose. Primare does not use a tube stage and these amps are still awesome and sound as good as any purification designs I have heard.  

Pascal modules are used in AVMs all-in-ones and some of the most expensive Class D amps made in Denmark.  The modules are expensive and sound really good and you could easily mistake this for a well manufactured bi-polar AB design.  

AGD was a staple for me for a long time and these amps sounded so good I found the closest comparison was to my tube monos, particularly the Grand Vivace's.  I am no longer an AGD dealer but that was driven by the fact that I did not make enough margin when taking trades. These sound like a Class A amp or AB that is biased heavily toward Class A.

NAD and Lyngdorf use Purifi.  I have said in another thread that the C298 is not the best amp I have ever heard, but it is the best $2K amp I had ever hear.  This was a few years ago.  I stand by that.  Brilliant product.  Clean and clear without edginess.  I would put this up against any bipolar amp under $10K and it will hold its own.  Lyngdorf is a different animal and the experience with them is about room correction.  Tougher to judge the amp.

The reality is Bob Carver's Tracking Down Converter back in 1995 or 96 was the first amp in this class that sounded genuinely good.  Bob knew what he had and patented it but unfortunately Sunfire never had the commercial success of Carver Corp and this stuff flew under the radar for a long time and it definitely skewed toward home cinema rather than two channel audio.   These amps were amazing sounding and delivered mind boggling current. Then Sunfire was sold and the product line just died.  

Linn's designs are proprietary and they do not use off the shelf modules so nothing sounds quite like them.  These are monster's in terms of current and power and deliver detail and clarity without edginess or fatigue.  These amps regularly deliver surprise moments where I hear a detail I have never heard in a song before.  It happens all the time and to songs I have listened to a lot.  They sound like an elite Class AB but you get 400w into 8 ohms doubling down to 2 ohm monos that are ~65lbs as opposed to 120 to 200lbs.  I have had these up against some big manufacturers and it is clearly taste driven at this level but they hold up.

Regarding Merrill, I have never had a trade in of these but do have a friend who has a set of their monos driving a pair of Magico M3s and his system is absolutely wonderful.  Sincerely a system that you can listen too all day with no fatigue.  Detail, power and clarity with no edge or harshness.  

Finally, I would mention Westminster.  WestminsterLab is Class A because its output devices conduct continuously through the full waveform (no crossover switching like AB or D), but it achieves efficiency by using a highly regulated, tightly controlled power supply and optimized bias that minimizes wasted current outside the linear operating window. In other words, the signal path remains pure Class A, while the power architecture is engineered to reduce heat and excess dissipation without altering the conduction behavior of the output stage.  Basically a Class A amp that behaves a lot like a Class D.  These things are awesome and I had a pair in for a few months and have heard them on some incredible systems.  

There are a lot of amazing Class D options, even at the cost no object level and they deliver.  I don't know why, with the level of elite performance we are getting from Class Ds these days, this is even a discussion anymore.  

Full disclosure, I am an NAD, Linn, Primare and AVM dealer.  I used to be an AGD dealer but the margin economics did not work with taking trades.  I am not a Westminster dealer but have a strong relationship with Hear This and am a dealer of other products from Gary.  I have no affiliation with any other brand mentioned.  

General update: I'm getting my hands on an AGD to try against the NAD M23. I will report. That will mean I've had three types of amps to try out in a short time – Hypex-based, Purifi-Eigentakt-based, GaNfet-based. I'm pleased about this.

I tried the NAD M23 with my 6SN7 tube amp last night. Zero fatigue. Other good Class D attributes were there.

@sdl4  Thanks. I'm not sure how critical the LPS is; I've heard there are now very good switching power supplies. I bet it has more to do with Ralph's ears and brain – to put it simply. I have a dealer near me (about an hour away) and if I can, I'll try his amps. 

I've also heard on a video that AGD's ganfets are from a supply that are specially audio-apt. Not sure what the others' are, but in all cases the engineer has to adapt his/her materials to the application. 

@verdantaudio 
Thanks for your long and descriptive post. Appreciate you relating your extensive experience.
I didn't find that a tube in front of a very well implemented Hypex/NCore took the edge off.

I'm curious about the Pascal modules, and obviously about AGD. The NAD M23 sounds pretty good but I appreciate your comment about the C298. That is sounding like a real bargain, especially used. Wonder if it could be modded/upgraded somehow to take it to the next level. I know a tech...

Sunfire story is super interesting! Really have not read much about Linn. You have me curious. Thanks for that!

The Merrill and Wesminster anecdotes are also very helpful. 

@ashoka  Your statement "class D was preferred because of Efficiency and cost." If that was all there was to it, you're right – there would not be a debate. But there is a debate, so...

@parkergetdean 
Super helpful to know about the SMSL PA200s. Jay Iyagi praised the heck out of them on a recent YouTube but then...

@greenngoldcheesehead 
It's good to keep in mind how good some of the class A/B amps are at doing what people laud about Class D. There's this notion that "Class D" are the future and then I think, "Wait – aren't there really good Class A/B amps out there? Yes, there are." But maybe they can't quite do what people like with Class D? Not sure, really.

@yyzsantabarbara 

Thanks for the GREAT description. Fascinating how a DAC can really impact even the strong sound character of the amp that follows, even creating, with the Class D 6.5 amp "a juicy Class A like sound." Of course, some people are not looking for a Class D amp with a Class A sound. They want something good but different than Class A. 

Good to know the 6.5 does not have glare; interesting that it was "lifeless" in the wrong combination. In other ways, it seems to really shine; makes me wonder about some of the SMSL amps. They sound like budget-helpful options, possibly. (Not necessarily for you, just generally.)