That is a very old preamp. My brother owned one back when I owned my KBL. I found it to be 90% of the performance of my KBL. This was if anything a bit on the warm side. I would be willing to bet your KSL needs recapped. Call the Krell service department. You have to be careful of DC issues when these preamps need recapped. You could really damage your Amp, Speakers or both.