I'm currently using an AVR1700, 5.1 but only in stereo mode. The speakers are positioned in the corner, they will move closer to the wall soon, but so far I've tested them about 3 feet off the wall. The bass is okay, its not insufficient, actually I'd say the mids being a little washed out is the bigger problem.
This new line of "green" H/K receivers -- I wonder if its not as warm as the older/higher end H/K receivers? The bass is ok, but the highs seem to be much more noticeable than the mids. Especially on something like electronica/trance. Whereas more acoustic/jazz/laid back music sounds quite good.