If you're happy with the sound, I would go with the Classe SSP-75. I personally prefer the Classe sound over the Krell sound also. It's richer and warmer in the midband, where the music lives.
I think you will be happy with either choice. I have the Krell HTS 7.1 & think the preamp section is a strong suit. I use my Krell with the Cary Cinema 5 amp, and the sound quality is outstanding. Prior to that I was using a set of Krell KAV series amps. Those amps were on the brighter side, but I think that is specific to that series of amps. Overall, I think the HTS is exceptionally nuetral preamp.
I have not heard the SSP 75, but have listened to the new SSP 30. It was nice, but I prefered the Krell. A recent review of the SSP60 indicated sound quality on par with the SSP 75, but with more features. I would propbaly be inclined to go with the newer design. I realize you are more into 2 channel, but the newer design has full bandwidth video and DPII (a noticeable improvement from DP). Can you audition the SSP 60 vs. the SSP 75?
Either way, you are looking at preamps which excel at the music side of the equation.
I preferred the SSP75 to the Krell in early 2002. I recently sold mine and replaced it with an SSP-60, and after break in, I concur that the 2-ch sound quality is very similar to the older unit.
The SSP60 costs $5K list, about 40% more than the going price on SSP75s ($3500 or so). However, I'd still recommend the SSP60 over its older sibling. Not only does it have the newer features, but it also corrects several annoying idiosyncracies of the older unit, such as losing the first note of any digital program and delays when switching sources.
I currently own the Krell HTS 7.1. I probably do 70% of my listening in 2 channel and can tell you that the HTS preamp section is OUTSTANDING. I don't find it bright at all. Krell claims to use the same circuitry for the preamp section that they do for their high end KCT preamp. I haven't heard the Classe but can tell you that since I bought the Krell, I feel like I have "rediscovered" a lot of my old CDs.
Best of luck with your decision. I have heard nothign but good things about the Classe. Can't go wrong either way.