M700 compared to Class A/B

Hoping to gain some wisdom and insight with the question.

I haven’t had much experience with Class D amps and what little I have experienced was over 15 years ago and it was not very positive. I currently have a two mono bloc configuration for my main speakers, Genesis 6.1’s, that seem to thrive on a lot of power. In this case my existing amps are 600/1000 wpc into an 8/4 ohm load respectively but are also biased at 60 watts of Class A. Suffice it to say they run hot and they are heavy. At this point in my audio endeavors I’m also intrigued with the idea of never having to deal with gear the weight of a yacht anchor.

Enter the M700’s. I love the look, the weight and appreciate the reviews they seem to receive. With a Class A Stereophile rating they are keeping company with some extremely expensive amps.

I have heard all else being equal Class D amps pack a larger punch watt for watt compared to Class A/B with a linear power supply. Is this actually true? And whether or not it is, will the reduction in WPC output I currently enjoy actually be noticed using the Stellar M700’s.

Thanks and I look forward to reading the replies.

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Just to complicate matters. PS Audio is releasing an M1200 with a tube input stage. they should sound amazing. The thread is here: New Generation PS Stellar, when?


Searching for answers on Class D ICE current output , it looks like the S300 delivers 20A, the M700 delivers 30A, & the yet to be released M1200 delivers 38A. Most large AB amps deliver 50A -60A on up.
My Apogee speakers are considered power hungry & your Genesis may be in the same camp.

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My power hungry 901’s with my personally rebuilt True Balanced Bose EQ run great with the M700’s. I used to be an Adcom Guy. Class D when voiced correctly (input stage Class A Transistors or soon Tubes) to my ears sound better than my old Adcom GFA-555II. It was a good amp in it’s day but for more critical listening, I like my McIntosh Killers (M700 x2 @ 350Wpc).


I have m700’s in my other system and they sound great, don’t run hot, are small, light, and very reasonably priced. Plus you have a 30 day return window if you buy them new. Pretty hard to beat really.


It can be true but that really depends on the design. Typical class AB amps have big power supplies with plenty of reserve while class D amps have big supplies with fairly low reserves. This is not something inherent in their design, just the way they are implemented.
In our designs—the M700 and upcoming M1200 in particular—we add power supply capacitance to try and equalize the difference in design.

This matters really only in sound quality IMHO (which is why we do it). Both designs of class D and class A are more than capable of driving your speakers from a current standpoint.

The bigger problem with power hungry speakers comes from impedance dips. There, both designs suffer equally. Your amp is either capable of handling low impedance dips or it is not. Ours can handle down to 2Ω and below that the protection circuit

Look for impedance dips and power output (headroom) as guides for your amps.

Everything else after power is all about soon d quality.


Where did you find these specs for the various types of amplifier technology?

Large A/B amps deliver 50-60 amps, seriously. I have never heard of this and if so seems it would be popping my circuit breakers constantly.


I hear you on that, and likewise I had already read through this thread too. Interesting development for sure.


Hi Outlaw,

In regards to PS Audio, I found it on the ICE website. It takes some digging & visiting multiple sites.

Some manufacturers will have this in their brochures or manuals. Sometimes a reviewer may mention it.

Wattage & current are not the same. For example, a Krell KSA 50 (50 watts @ 8 ohms) would easily drive Apogees, while a ARC D200 (200 watts @ 8 ohms) would leave the Apogees lifeless. It’s all about current.

Hope this helps.

Rasputin says

Interesting info thanks! I see you have Apogee Speakers. An old friend of mine and past customer when I briefly worked in this industry has a pair of Apogee Studio Grands which I swear are still the best speakers I have ever listened to.

Years ago he was driving them with a pair of Krell Audio Master mono blocs. Well I think that is what they were called. So one evening I brought over a small 42 lb stereo amp that Inner Sound at the time was having produced. Cutting to the chase this Inner Sound amp completely annihilated the big Krells, not even close. Of all the audio comparisons i have ever done this was the most profound one ever. There were some half dozen seasoned audiophiles in the room that night, and all agreed and will often refer back to that comparison. The difference was so dramatic we were all laughing about the plausibility of it through out the evening. Don’t recall the number of output devices per channel on that amp, but it was a lot… perhaps 18 per side if memory serves me correctly.

I suppose that means lots of current.


I remember those Inner Sound amps & speakers. If the sweet spot was wider I would have bought them.

Jason Bloom was big on low end performance & enthusiastically endorsed Krell. Especially during the Scintilla & the “Apogee” days, Most users thought it was a coin flip between the Classe DR amps & the Krells. Both were high current amps.

Theee are quite a few interesting amps, unfortunately these amps are not being mated with my speakers, that is why I’m placing peak current as a priority.

I’m trying to determine “How much current does one need” also in that search.

I know that the BHK amps deliver more peak current than the S300’s or M700’s, but the days of large heavy amps are over for me.


I’m going to investigate the Benchmark amps for suitability. I would need two & they deliver 29A. The M700’s deliver 30A & I would need two pair. The cash outlay is the same & they’re small & light.

It might come down to 4 monos or two stereo amps.

To throw another contender into the ring I would consider Bel Canto Ref. 600m monos. New they may be out of scope, but used they can be had ~$3000/pair if you are patient. They use Hypex Ncore modules instead of Ice and the consensus is that the Ncore single-handedly changed the digital game to sound, well, not digital at all.

I use three of them for the front stage of my home theater (left/center/right channel) and enjoy them thoroughly.


Agreed that was the one big downside to the Innersound electrostatic speakers. There was another issue within the design of those speakers I never understood either. The crossover point between the panels and those 10" woofers was at 350 hz, smack dab in the middle of male voices. This never made sense to me and can only believe those panels had the ability to perform very well at least a couple of octaves lower.

Regarding the Apogees, it was my understanding those Krell Audio Standards were designed specifically for those speakers. Price was about $26K per pair if memory serves me correct. It didn’t matter though with a small amp at 1/10th the price literally, putting the big heavy Krells to shame.

Not sure how one would go about determining how much current is needed to properly drive any speaker, but an interesting concept though.

Wyred for Sound also makes some high powered digital amps at 4 ohms they put out something like 1200 wpc. I have never heard any of their products but they seem to enjoy very positive reviews. As well I know one person who had a huge 100 lb linear power supply amp that traded down to one of their stereo amps and likes the sound much better, go figure.

Lots of options in todays audio world.

I have a pair of class A/B Odyssey Audio Stratos Mono block amps with these specs (per amp):

800 VA transformer
180,000 uF capacitors
120 amps current delivery
2 Ohm load stable

These amps are 16 years old, and I should really send them back to the manufacturer to replace the caps. However, finding packing materials to box them and sending them back is a hassle I don’t want to go through, and I really like the style and the light weight of the PS Audio M700.

My question: How do my current class A/B mono blocks compared with the M700? And how do they compare driving a pair of Magnepan 1.7i with 86db sensitivity?

Thank you.

Well, I can tell you the M700s sound killer on Maggies and are certainly up for the task. They would shine big time on that setup. I cannot tell you how they would compare with your Odyssey amps because I have never heard them. I would suggest grabbing a pair
from us and playing with them at home. Then, let us know. Maybe trade those old ones in on the pair of M700s. You can keep them at home until you make the decision and we don’t require original packing. Just a thought.

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