6/10 condition to be fair due to a few scratches around various parts of the chassis.  No bent fins on the heat sink or other major cosmetic dings or significant scratches.  Unit has been semi-inactive over the past decade with only minimal use.  The amplifier has rigorously been tested and is in perfect sonic shape.  This unit has not been recapped or serviced, but doesn't appear to have any issues with leaks in the caps or other operational issues.  To say this amplifier sounds fantastic is a criminal understatement!
 

"I suspect that even the Krell team was surprised when the Full Power Balanced 600 began to take shape. On paper, it was simply a power-doubled FPB 300 delivered at a moderate and appropriate hike in price. In practice, the FPB 600 has gone much further. Great as the '300 undoubtedly is, the '600 holds all the aces, with a potential to severely embarrass a wide sampling of top-brand power-amplifier references. I'm quite certain that it redefines the art. It will certainly dictate a vigorous shakeup of the current stack of Class A power amplifiers in Stereophile's "Recommended Components." Since a Class A rating means "the best we know," I feel that, in the light of this design achievement, the rest will have to be re-classed (footnote 2).

The FPB 600 advances substantially on the FPB 300 in particular, and on the art of the power amp in general. In fact, I suspect that the Krell designers are now acutely embarrassed at the audible shortfall in matching preamplifier performance. With no disrespect intended to the KRC-HR (Stereophile, October 1996, Vol.19 No.10), just use one in conjunction with the KPS-20i/l and the FPB 600. Then bypass the KRC-HR by simply linking the existing balanced cables input to output, with no other changes whatsoever—and hear the system take off. Such is the '600's transparency that care in system alignment, choice of cable, and quality of connectors all offer substantial payoffs.

The FPB 600's sound quality was at the leading edge. The Wilson X-1 Grand SLAMM proved as nearly perfect a match as one could wish for. The overall quality and dynamic range available from this combination was both stunning and breathtaking.

Add into the equation its huge, uncompromised peak loudness, the incomparable power delivery confirmed in its excellent laboratory results, and the Krell FPB 600 is something quite special among power amplifiers. And, lest I forget: at the price, and taking everything into account, this big Krell is actually good value for money.

I confidently dub the Full Power Balanced 600 the "Grand Slam" of power amplifiers."  -Martin Collums "Stereophile"