Best Integrated amp for under 4k

Given that this thread has been resurrected, I'll offer my two cents. 

Musical Fidelity M6si

TY- jmvs

the only caveat of the 330i and 550i, is that, both were made in china.

The Krell Vanguard is the best sounding integrated that they've ever made.  It does everything well.  Speed, detail, huge soundstage, bass depth and snap.  It takes a lot of money to beat it.  It retails for 4500, slightly over the original poster's price, but can probably be found for ~4000 without too much trouble.  It's an awesome sounding unit.

herndonb

I really want to demo this Krell Vanguard. What other gear, including Cabling, is in your system?

I just upgraded to a Marantz PM-11S3.  Bought a gently used one for well under your $4K budget.  Love it.