See if you can borrow a better source component (a Benchmark DAC-1 perhaps?) before driving yourself crazy with speaker placement. I know speaker placement is very important, but you have very high resolution electronics, speaker cables, and speakers, and a CD player that's not in the same league. Maybe the Krell/Kimber/Forest signal chain is revealing the Yamaha's shortcomings.
Your room and placement is asking for trouble--same resonating frequency for all four walls, half the wall length for the space between the speakers, and 1/4 the wall length for the space between each speaker and its wall.
Your room and placement is asking for trouble--same resonating frequency for all four walls, half the wall length for the space between the speakers, and 1/4 the wall length for the space between each speaker and its wall.