I think you're speaking of the IcePower amps used by companies like Jeff Rowland Design Group and Belcanto. IcePower was used in a Bang & Olofsen self-powered speaker, but it went through years of development before it was licensed to other users.
It's an off-shoot of Class D (it IS NOT digital, as there's no analog-to-digital or DAC).
As you might suspect, high end designers don't just take an IcePower unit and stuff it into their own case then mark it up a bunch for a nice profit. There's a lot of design work going to such things as power management, filtering, RFI and EFI protection, etc.
I know more about Rowland because I own a Continuum 500 integrated amplifier with phono section. Part of how Rowland achieves ultra-quiet operation is with Power Factor Correction which converts ANY AC line to 385V. After listening at 85dB average I can turn off the source, put my ear to the tweeter and not hear a thing. It takes another 10dB before I start hearing anything, partly because any chance for 60-cycle hum has been removed.
As your read around the forums you'll see a lot of negative energy about IcePower or Class D. I think that's way out of date. In the best incarnations it can be incredibly transparent, detailed and stress free.
Listen for yourself. I don't know your wyred4sound amp, so I cannot comment on it specifically. Since there's a lot of variance in application of IcePower, you'll need to listen with your own speakers. If you can hear Rowland or BelCanto, do.
I would like to know how they perform with low impedance, low efficiency speakers like Totem Mani-2?
All the class D amps I've seen will double their power output when the load is halved. They all have an RF filter on their output, yet they still produce a lot of ultrasonic noise. JA measured 1.2V RMS for the Bel Canto e.One in this month's Stereophile. So it has a whopping wideband S/N ratio of 8dB! Also, look at the 10KHz square wave in Fig.2 on page 108. It's better than some he's measured, but still nothing like a good class AB amp.
Of course, none of this matters if you like the sound.
I have PS Audio GCA 250 with Underwood HiFi level 2 mod running my Magnepan 3.5R ribbon tweeters and a pair of Wyred4Sound SX 500s on the mid/bass panels. Tough lods to be sure, but the amps handle with aplomb. Fabulous sound, too!
Stereophile's testing of the Totem showed it dropping to 3 ohms, which will not be a problem for any IcePower or Class D amp that I know of. The high power tends to work very well with relatively low efficiency speakers needing lots of current.
I do love my Bel Canto M300s. The reviews are pretty much all over the map, as you have seen. Also, the measurements are weird and as in tube amps don't tell you how it sounds. There is something about the synergy of these amps with the speakers. My advice is to audition them in your home first or buy with the option of returning them. Don't believe all the comments you read on line. Trust your own ears.
I'd take a look at the Spectron Premier. It 'breaks the mold' on the limitations of what most people associate with Class D amps.
It sort of combines the best of tube and good SS amps without any veil to the music. The frequency range is very flat, the highs are extended without being bright or harsh, the midrange is very liquid and the bass is very tight and rich.
You can view the professional and user reviews on their website.
As a matter of disclosure, I am an authorized dealer for Spectron and became one becasue these amps are phenominal.
I have a new multi-channel Wyred4Sound ICE amp and it is, frankly, astoundingly good.
And, in fact, I'm going to take this opportunity to apologize to Mr. Bob Reynolds for previous comments. I indicated he was crazy if he could not tell the difference between a SET amp and a class AB solid-state amp in his system. Well, would you believe that this ICE amp sounds so close to my 300B set that differences are a matter of subtleties? I can now readily tell them apart, but at first they appeared nearly identical!
Before anybody thinks the system is unresolving or I can't hear, I'll add that switching between two world-class linestages, both tube, in this system, produces sonic differences to the extent that I can almost literally tell them apart from the first note. They're both great - but very different.
The funny thing to me is that I paid $800 for WE 300B output tubes to get that articulation and linear sound. If I were using cheaper 300Bs that invariably sound a little rounder, the differences would certainly be less subtle.
Please don't gloat too much, Bob, because most SETs still sound quite different from most AB transistor amps. Heck, most SETs sound quite different from *each other*, with each output tube have a distinctive set of characteristics.
H2O amps drive 1-ohm Apogee Scintillas!
I had a D-sonic with 525 watts per channel on my Vandys for a couple of days. While the sound was nice with good detail and transparency, it did not seem to image well and the soundstage was rather linear exposing the speakers. I mean that the sound appreared to come from the speakers themselves. With good imaging and soundstaging, the speakers tend to disappear which it did with my TAD-60 and does even better with my TAD-125 monos.
The Bel canto e1 is one of the best amps I have heard. They will drive any speaker, they are small, powerful and utterly transparent.
I had the Jeff Rowland Ice power monos too, but felt the Bel canto was a wider, fuller/richer sounding amp.
These ICE power amps make a fool out of many expensive amps that need huge transformers and heat sinks which all add to the cost of the amp. They leave many amps sounding veiled and slow.
Many on the gon dislike these amps. I have a feeling it is not the amp they dislike but other parts of their system that is being revealed. They have no sound really. Simply stunning amps.
An amp/speaker system is in fact a single, closed system since there is bi-directional interaction, and speakers are voiced with particular amplifiers or amplifier topologies. Thus, speakers voiced with, say, SET, or even many SS amps are not going to sound right with an ICE or other switching amp. This, of course, is not the fault of the amp. I think this explains a good deal of the negative reaction to switching amps.
you are right of course, and this is why there are so many manufacturers all believing they make the best set of compromise in their design. It makes it very confusing for people searching for the best hifi combination and probably fun too.
I have heard people say the switching amps strip timbre information when compared to their amp. Something which I have never found. In fact I would say the opposite especially with the Bel canto e1.
In fact in my system I cant fault it at all.
Right on Chadeffect. If more people would just listen for themselves, things would be simpler.
BTW, great system(s), old and new.
"H2O amps drive 1-ohm Apogee Scintillas!"
Do you watch SNL? If so may you remember (about 10 years) ago cat Tootsie - the cat who could drive the car but...not very well.
All The best
P.S. I am not familiar with H20 they could be fantastic amplifiers - just your statement was funny. So what that some amp drives some speakers. The question is "how well"?
You're dating yourself - Toonsie was more like circa '91. :)
The answer is; very well indeed. Even H2O's entry level Signature 100 stereo amp is stable powering the Apogee's midrange panel (0.3 ohms)- and can effortlessly do so might I add.
Sound quality? Thats as subjective as it gets. Personally, its one of the few ICE amps I've heard that I can live with.It's also one of the few affordable powerhouse amps I've come across that can sound as delicate as an integrated with an extremely simple and small circuit (ala, red wine audio sig 30). As always, this is all my own observation - so take it as such.
I'd recommend H2O Products, but they are disqualified for being relatively large, and quite heavy. Thankfully, there are plenty of slim line ICE options that are suitable for HT use. Wyred4sound, D-Sonic, PS Audio, etc.. etc..
Good luck with the class D hunt Docrobbi
It was "Toonces" NOT "Toonsie"!!