With Krell you might have what you want now.Many folks here on 'Gon have come to the oppinon that 20 amp line is all you want maybe with the Outlets but a power conditoner will limit current.I'd buy new with ability to return.
I am not sure which series of Krell mono block amp you have, but the FPB has some sort of conditioner designed into the amp to address fluctuating AC power. I have the Krell 650mono's plugged into 30amp dedicated lines, but with a 20 amp plug configuration, and running dedicated lines is a major improvement in sound over the standard outlet used prior. Next, I want to experiment with the higher quality AC outlets others on Audiogon have recommended.
I plugged two FPB 350s into a single Ultimate Outlet on a non dedicated line and heard improvement in the system. Although not night and day, the Krells opened up a bit more with even better bass. Bybee Signature conditioners also work extremely well. No offense to Verastar, but conditioners with large transformers other than a Variac usually limit the dynamics and bass on the big Krells. I once tried an FPB600 with Furman's reference conditioner and noticed limited dynamics and closed in bass. You never know until you try one in your own system though.
I use a Sound Application Linestage with the Elrod cord to great effect. It is a articulate Krell now that still has that great bass Krell lovers like.
I also own the UO high current using a PS Audio power cord and also used with many other many other power cords and found an improvement proportionate to its cost, but the Linestage is the greatest I have tried to date.
I find line conditioning works.
I use 10awg solid wire to a 30 amp circuit with the 20amp cryo Hubbells.