Need Advice on Multi-channel Amp Choices.

@erik_squires - why are you suspicious of multi-channel amps?  Is it because of the shared power supply?

I would probably not look at the AudioControl amp because it's Class H.  They are usually used in pro-audio where it requires a very high power amp with efficient power supply.  I had a Crown Class I amp and it sounded good (although it had it's own tube-like signature), but it did not compare to a normal high-current amp with linear power supply.  Class H is another way to create

In your three choices I would choose the Classe CA-5100 first and I'll tell you why.  I took a quick look at the Arcam AV950 and I would guess it's using an opamp based audio stage with no Class A biasing.  You can look at the pic below, the power supply is very small with tiny heatsinks for voltage regulators.  A processor with a Class A audio stage would use larger heatsinks because it pulls more constant current/power.

http://www.hifitest.de/images/testbilder/thumb_slider/arcam-av950p777-av-kombinationen-29280.jpg

Each channel of the Classe CA-5100 is biased into Class A for the first 30 watts.  This will definitely help give you more body/thickness in the sound from the Arcam.  It may also help give you more solid bass/midbass.  The shared power supply might give you a little more punch on midbass.

The Earthquake would be second choice.  It has shared transformer, but individual capacitor banks for each amp channel (only 22,200 uf per channel).  Nice for channel separation, but for home theater may lack some meat/punch.

If you had a processor that ran in Class A (like a Bryston or Krell), I might recommend the Earthquake.  It's a hard call.

This next suggestion might be an amplifier older than what you are looking for, but the Krell Theater Amplifier Standard was an exceptional multi-channel amp.  The amp output stage is Class AB, but the driver stage is Class A, so you will still get some benefit here, and the power supply is a lot larger than the others.  It may be too old for you (probably about 15 years old).

http://www.ebay.com/itm/krell-Theater-Amplifier-Standard-Multi-Channel-Amplifier-/262651327143?hash=item3d273d32a7:g:mf8AAOSwmfhX7tJb

This was 7-8 years ago when me and my cousin were into Class D amps for a while. ICE and Hypex UCD were the only two. We were using the Channel Island which had the Hypex UCD - we chose that for some reason I can’t remember (it may have been the design of the negative feedback, not sure). What we experienced was that it drove different speakers differently. I had some Focal speakers that were easy to drive. However, when put on a Aerial 10T, it had good midrange body, but we lost all bass punch/impact and the highs were severely rolled off. Others had problems with the Channel Island, such as pairing with B&W Diamond. When we matched the 10T up with an Aragon 8088BB high-current, the problems went away and the sound was significantly better.

That being said, the Channel Islands did well with the Focal, but we could tell that it wasn’t perfect. It did have a somewhat forward sound, as some frequencies were pushed and others were not (the high frequency rolloff actually helped the Focal a bit).

Moving on to B&W Diamonds. I had a Crown CTS2000 - Class I (variation of Class D). It was decent, but the Crown had weird tube-like overtones and wasn’t exactly neutral/dry. The Channel Islands did much better. But when I put on an Emotiva XPA-1 (high current), it pretty much blew the other two away.

There was an article/document I read years ago about Class D - I can’t find it anymore. The guy had worked with Class D amp design a lot. What he said was that the speaker itself must be part of the Class D circuit design and influences the circuit itself. So, in a Class D circuit, the engineer has to make some design decisions on the assumption of what kind of speaker is going to be placed. In a perfect world, a speaker with a flat 8 ohm impedance (across the entire frequency range) would be very good. However, when the impedance starts to go all over the place, it will influence how the Class D circuit responds. (don’t ask more I cannot technical explain more than the bits I have remembered from the artical which I stated above).

A linear Class A/AB amp will still be influenced by the speaker impedance curve, but it is much more resistant to this when compared to a Class D circuit.

I don’t know how nCore compares as it wasn’t around at that time. It could be something related only to Hypex UCD.

Thanks for your additional comments, Eric.  It may be that the newer ICE and ncore amps work better with difficult speaker loads.  I did some quick browsing on ICEpower and nCore.  One of the things that stood out was that nCore was designed to remove any coloration on the sound - extremely low distortion.  The idea was to reproduce exactly as the sound was input.  More searching indicates that this is the nature of these new Class D amps - no coloration.  Some have commented that they are lean or a bit bright/cold.  I do not have any direct experience with ICE or nCore, but it could be the preamp/source that is dictating this nature.  The Wyred 4 Sound amps use ICEpower and I know the general approach from Wyred is to make things as transparent as possible.

I'm wondering if the listener experience is dictated by the preamp/source.  If they are using an opamp based preamp/source, the nCore may be too transparent and you end up getting a lean/thin sound.  When paired with a Class A or tube preamp, the nCore may really shine - as you are putting a limit on how much coloration is going into the audio signal path.  The only thing that catches me here is that you could not hear any difference between ICEpower and the Parasound A23, which is very interesting.

Don't know.  If you pair the nCore NAD M27 amp with the Arcam AV950, you might not get that sweet/full sound - it may be too much transparency.

Thoughts?

@erik_squires - yes, I do agree with all your points on multi-channel amps. It is, basically, a compromise to get 5 or 7 channels into a single device and still perform -somewhat- well.

The Monitor Audio speakers are 4 ohm, which will make it more difficult for an amplifier to drive. However, it doesn’t really drop down below 4 ohms like some speakers do, and most of the impedance is readily above 4 ohms:

http://www.stereophile.com/content/monitor-audio-platinum-pl200-loudspeaker-measurements#6kWsTrvo8jKsRcRR.97

That being said, you will probably lose some midbass punch where the impedance is almost a flat 4 ohms between 100 and 200 Hz. Also, some areas in the deep bass. The Classe amp is probably the best choice out of your 3 because of the "Class A" bias, but it is not really the best choice for the speakers.

Yes, nCore and ICE Class D amps can generate more power, but in my experience in research, the frequency response of Class D amps are typically dictated by the speakers impedance curve, meaning that the lower impedance areas will affect how powerful the Class D amp outputs. A Class D amp will probably perform very well on a speaker that is almost a flat 8ohms across the entire frequency range (much like a basic 8 ohm resistor). I don’t know about the newer Class D amps, but this is what I found with earlier Class D.

I don’t know if you are taking suggestions, but I have owned the B&K Reference 7 channel before. It’s more power than the Classe (at 200 w/ch). It has a Class A pre-driver and good power supply. The amp had really good power and volume and it was very sweet sounding, but I felt that the sound was too warm for me. At the time, I was running a Bryston SP2 Class A processor, so it was too much Class A in the audio path for me, but I think it could work out for you if you want to consider it.

https://www.audiogon.com/listings/multi-ch-b-k-components-reference-200-7-s2-7-channel-power-amplifier-9286-2016-09-20-amplifiers-80020-broomfield-co

Otherwise, another suggestion is to start buying up used Emotiva XPA-1L monoblock amps and run them in the Class A mode (30 watts). They are typically less than $400 each used, so it is in your budget. The only problem is supplying a separate outlet (or heavy power strip) for each amp. You need space for 5-7 individual amps and they do get hot in Class A - so you will need a good 3" space above for heat ventilation.

I was just looking around and came across this Classe CA-5200. It is twice as much as your budget (around $2k), but it has a shared power supply twice as large as the CA-5100 -- at 200w/ch 8ohm, 375w/ch @ 4ohm. It’s expensive, but if you were liking the idea of Classe brand, you could look at this. It is a beast at 121 lbs (like the Theta Dreadnaught), but I think it will do better because of it’s huge shared power supply - akin to the Krell Theater Amplifier Standard.