I agree with Unsopund, the original KSA 50 (NOT the KSA 50s) was a pretty nice-sounding amp, particularly in the Mark II version, probably one of Krell's sweetest-sounding units, but it would likely need a full blown refurbishing, which would be expensive. In addition, it was fan-cooled, a part which could break down over time, and a pure Class A design, which means it really needed that fan--Krell ultimately started using heat sinks in its later designs in part for that reason. The strength of the first Krell designs was their ability to drive virtually any load; my KSA 50 did fine with my Duntech Princesses (90 db efficiency), though I ultimately opted for the more pwerful KSA 80 because I felt I needed a little more headroom. I think in retrospect it probably sounded a little more hi-fi than natural, but I have been converted to tubes since I owned it so take that for what it's worth.