I have been using a Krell FPB 300cx in my Main System since early 2003 and have never found a reason to "upgrade," if that is even the proper word. The amp has never even had a hiccup, much less given me a problem; sounds excellent on all types of music; and is very powerful, provides deep, taut bass, is full-bodied and sweet musically; Plays well with diverse pre's and cables. The speaker terminals are the best in the biz -- big wing nuts easy to use and providing tight connections.
Does run a bit on warm side so you need to give it room on top. Only other downsides are that it,(i) provides only balanced inputs, so I have has to use adapters because my Wyetech Opal pre has only RCA outputs (Cardas and BAT make excellent ones) and (ii)has a captive PC so you cannot experiment, of course with no assurance you would do any better. I run it through an Audience AR6 conditioner and it sounds grand.
As they say in the infomercial: Set it and forget it!
Neal