Tube-pre and interconnect match for Krell FPB-300

After spending some time with my B&K Ref 30 and my Krell FPB-300, I feel like I may be missing some of the 2 channel material. I'm happy with the authority and control of the Krell so I thought I might upgrade the pre-amp. The equipment is also part of a home theater but I have other amplification if the experts on this site think I need to remove the Krell for a music-only rig. This is eventually going to be a total upgrade from source to speakers(as $ allows) so any recommendations would be appreciated for all system parts. I'm currently leaning toward used B&W Nautilus 801s/802s or similar for speakers(I can't afford any of this new!).

I'm particularly curious about how tube pre-amps, with which I have no experience, match with Krell amps and what interconnects would work well. I hear so much about how musical tubes are.
I would really appreciate comments from anyone who has had a fair amount of experience with Krell FPBs. I admit I have very little experience with all except my current equipment. Thanks so much in advance.