Bel Canto, Nuforce, Acoustic Reality, Channel Is.

I would not recommend any of the following you have listed, under your criteria you are looking for a "warm..." natured amp. Of the ones you list none would be classified "warm" IMHO.

If you are seeking the type D amplifier, you should also add to your list the H2o.

Almost all class D type amps pride themselves on linearity, clean power, and neutrality. Thus why I mentioned I wouldn't term any of those you listed as "warm."

The H2o has been reviewed against other amps of this type and found to have the qualities you are seeking over other amps of similar type. You can read this for yourself in the
6moons Review

H2o Audio Website

Good luck on your search!

Actually, I may stand corrected.

I have not heard the Channel Islands yet, and have heard from people whom's opinion I respect they are a decent contender.

Of the others you listed, I stand by my comments. Others I have auditioned prior to my H2o purchase were the Rowland 201's & 501's, Bel Canto Evo 2's... I wouldn't add them to your audition list over the H2o's.

I'm in general agreement with what Tvad and Slaw3 have posted. The CI may be less bright and a little warmer sounding than the NuForce or AR amps. With any of these amps, going straight in from the Wadia could yield a bright presentation from the Sonatas.

I think James was on the right track. What I recommend is buying a Monarchy M24 tube DAC/Linestage and using the Wadia as a transport to feed the M24's DAC stage. Put a pair of Siemens E88CC gold-pin tubes in the DAC stage. You'll need to use the Monarchy's tube linestage to get volume control and you can play with the two tubes in the linestage as well. The stock military Russian 6DJ8s are not at all bad.

In my view, you'd move a lot closer to the sound you've described by using a tube DAC or a tube linestage -- rather than changing amplifiers.

If you go to a good tube unit and still want a little more dynamic pop and slam, the NuForce Reference 9.02's should fill that bill nicely.