Well Hello!
I use to own a pair of Polk Audio LSi9's the only reason I sold them was for space. If anybody tells you those speakers are mid-fi tell em to check their ears at the door! What an underrated speaker; they really beat the tar out of some higher priced 'highend' stuff I heard at CES.
I went from using a NAD 320BEE to a SimAudio I-5080 and later on moved to the Krell 400xi. I found the Krell was by far the best, even out of the box the Krell gave me goosebumps! I don't get goosebumps much anymore. I'm not sure what kind of music you listen to. If you prefer Jazz a SimAudio might give you a little bit of a more organic sound but if you're like me and listen to alot of everything then check out the Krell 400xi used.
Speaking with Timhr, I almost opted for a Classe' CAP 151 instead of the Krell; I'm sure both would be close. A SimAudio i-5 would work as well; although I found the SimAudio to sound too flat for the already very laid back LSi presentation.
Enjoy whatever it is you purchase!