I have owned a lot of Krell gear (although not the 80B) and as I went from one level to a newer one, the sound always improved.
I just upgraded from a KSA-200s to FPB 300cx. The improvement in high frequencies, impact, and inter harmonic detail was amazing. I ran the 200s with a SF Line 3 which was a very good match. The 200s is a little bright so a tube pre amp is a good choice in general (dont get the ARC Ls2b. That combo will drill holes in your skull.
Just upgraded the preamp to a Ayre K1xe for another improvement.