Tube amp suggestion

Almarro also has a beefier tube amp that may be good.

@Lewinskih01 to answer your question, yes the 805D's have two sets of binding posts. As far as tubes for top end and SS for bass? I really don't know, as I said before, I don't know enough about tubes to know what to do, go tube amps for highs and lows or tubes for highs and ss for lows.
Also, budget is also a consideration.

I'd say try to audition an MC275 with 805D. Might not be that difficult as many dealers carry both lines.

Again, with my 804S the Rotel didn't provide better bass than with the MC275, so don't assume SS will outperform tubes ALWAYS.

If you can swing it, get the tube amp you choose, play a bit with biamping and decide which way to go. I chose for a single amp and upgraded the preamp with the sold amp.

To properly biamp you will need an external crossover, plus an extra sets of ICs and 2 extra power cords...and the extra amp, of course. Is it worth the extra cash? Your ears will tell you. In my case I went for better electronics, but YMMV.

I hope it helps.

Maddog,
When you say, "my cables are already set for biamping", what exactly do you mean? Do you have 4 spades per channel at the amp end and only two per channel at the speaker end? Re-termination should be a minor concern vs. your other questions.

Yes, you can add some warmth by using a tube preamp w/your ss amps. This is a common step many in your shoes take. But that won't do what a good tube amp will.

IMO, simplifying with one good amp would be your best bet. Yes, it does need to be capable of driving your speakers and best way to get a handle on that is too post a thread titled "What tube amps go with B&W Model XYZ" etc. People who have experimented w/that will reply. Cheers,
Spencer

Sbank, that's good advice.