Totem Forest Speakers.....

My Forests sounded best about 2 feet from wall, 8-9' apart, toed in to the listening position, and mass loaded (about 50% of bottom chamber filled with small river stones -- there's another recent thread on mass loading). They also sounded better without grills, after 300+ hours of break-in and with the right cables. Ultimately prefered copper wire over silver with the Forests. Quite a few different amps of very different designs worked well with them, but they all had plenty of juice.

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.

You're suffering from garbage in, garbage out.
Great amp and speakers!

Matt, synergy is so so elusive. I'm still trying to capture it in my system. Source amp speaker synergy is complex or can be simple if you know of system(s) that work well and replicate that system. The Yamaha appears to be the lesser component in your system. If I were you I would look at the source first and replace it. If you then do not get what you are listening for then look at the 400xi and replace it.

A square box is the worst scenario for acoustics. The Krell sounds average to bad with the stock power cord and run un-balanced. You shoul run it balanced with a musical CDP and a great PC and interconnect like MIT offers. If you want good advice from a veteran in the business call Joe Abrams at Equus Audio (Portal Audio). He will cut through the "well intentioned advice" you are getting and give you some solid options to pursue:O)