What 2 channel Amp would you Buy for $6k?

Find some Krell Fpb 350m or mc monos . Not the mcx or 250m. Different world . 

It is hard to give advise without knowing more about your system's needs
How efficient  are your speakers, What other components are in your current setup.
Do you require a balanced design.
Power amps can run the gamut from warm to bright in sound with small power output to very large
Matching components for synergy from the Audiogon community will be far more helpful
Dennis
 

Sanders Magtech

I snagged a mint condition McIntosh MC452 which was something like four months old when I found it on Audiogon.
I really enjoy this amp, which is driving a pair of Focal speakers with that beryllium tweeter, which I found sounds too "sharp" with other amps, not the McIntosh.
You can probably find a mint-condition MC452 for your price range.  If you do, please have a friend help with the unboxing and positioning, as this beast is heavy!

@roddyboy - Are you looking for people to just throw out the names of the amps they currently own or really like, or are you looking for some advice as to which amp is maybe going to work in your room. If it's the latter, more information is needed.