Tube amp suggestion

@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.

I'm considering moving from solid state to tube amps but don't really know where to start. I currently have:
Pair of B&W 805D
Marantz sr7005 (setup as a preamp)
Pair of Rotel amps, bi-amped

As mentioned above, start with replacing the Marantz with a good tube preamp. A lot of the benefits of tube amps will be lost going through that receiver.

I've owned Rotel(980BX or 990BX) amp and preamp, and low-end B&W(301), and while great equipment at their price point, I found their sound together lean and flat. Obviously, the 805D is far better than what I had. But, I tried the Rotel with a few other speakers and still found it to be a little lacking for my taste. Also, I have spent quite a bit of time listening to the 805's at a friends house.

As for the Almarro A318B suggestion, I have also owned that amp for a good amount of time. It is a superb performer far above it's pay grade. I used it to drive 90dB/4ohm Jean Marie Reynaud Twins nkII monitors. The match was fantastic. And there is some unique about the 6C33C SET sound - incredibly transparent, almost no discernible character of it's own unlike other Triodes. The big advantage is that it is an integrated amp, so you wouldn't need to use the Marantz.

But, 18wpc SET will not be everyone's cup of tea, depending on room size and musical listening preferences and average volume.

A safer suggestion would be something with more power like a used Manley Stingray integrated.