Offline69, the KRC2 and KRC3 were made at different times. The KRC2 preceded the 3 and many feel that the proverbial "improvements" Krell claimed did not result in a better sounding product. Many people feel that the KRC-HR is the best of the family (so to speak), followed in this line by the 2.
With your B&W speakers, I would stick with SS preamp if you are not comfortable with tubes. Though they are not as scary as some make them out to be - both the hardcore tube rollers and those that warn of tube failures happening all the time, the high risk, etc. . . Tubes in a preamp are pretty easy and you can get some great advice. If you do go to tubes at some point, the preamp is a good starting point.