08-16-14: Zd542
My recommendation for you would be to consider getting something to replace your Krell first. Personally, I feel that is your weakest component. Of course, others will not agree with me.
I'll second this recommendation. Yes, you can do better than the Usher's, but the Krell seems like the bottleneck to me. Krell's stereo amps and not bad, just over-priced, but the KAV series leave a lot to be desired, IMHO.