Just to clarify - three of my amplifiers (front L, C, and R) are equipped with differential inputs; presently, I have another older two-channel amplifier with RCA inputs to handle two of the rears - and I don't have the other pair of B&W 805's...yet (though I do have two pair of the 805's and the companion HTM center channel, as well as a Velodyne F-1200). Anyway...the rears sound pretty damned quiet as well. I will say this...I may need to re-arrange the equipment rack(s), so having balanced outs and differential-in amps gives me a lot more flexibility in terms of where I can locate the amplifiers relative to the pre-pro.
Anyway, differential inputs are the natural companion to a balanced output (I won't go into the why and wherefore as it's been covered in many places...and I really don't want to stir up the pot). Unfortunately, I have not been able to find more monoblocks for my system for the surrounds as they are out of production / available on a custom-order basis (read: pricey), that is, additional monoblocks like the three others that I have (DB Systems' DB-6M, modified by DB Systems to incorporate differential inputs, additional power supply capacitance etc).
There is always ebay....
Anyway...the transition to multi-channel from two-channel is turning out to be a pleasant experience. Like I said...I can't see spending more than I did for the 990 and getting what I got. Yes, I looked (closely) at the B&K and the Anthem pieces, but just couldn't justify the additional dough.
Now for the tough part...trying to decide where / which rooms will get all my old two-channel gear. This will of course require that I find some 'nice' speakers for those rooms; I can't bear the thought of selling all the gear I have been collecting over the years. Furtunately, I have my Audiotron DAR's available (playing uncompressed files) to stream the library from my host PC into each room...as well as the 990.
Life is good.
Mark