I think the Krells matched to the Pass would be OK, but not exactly synergestic.
A good interim between tube and solid state is the Herron preamp, a tube heart but the soul of a solid state (did I really just write that?). Tight bass, fast transients, and liquid like mids and highs without the dark signature of tubes.
If it means anything to you, TAS, Ultimate, Listener, and Stereophile all have voted for the Herron.
Good luck. (It's about $2,000 used)
A good interim between tube and solid state is the Herron preamp, a tube heart but the soul of a solid state (did I really just write that?). Tight bass, fast transients, and liquid like mids and highs without the dark signature of tubes.
If it means anything to you, TAS, Ultimate, Listener, and Stereophile all have voted for the Herron.
Good luck. (It's about $2,000 used)