Thoughts on SS bass. Tube mid and high tube pre

Assuming the Bryston's input sensitivity is close or identical to your other amps, go for it!You should get much more bass energy than now.BTW, you do have a pre (or a volume pot) somewhere in the system? Regards

The Tannoy Monitor Gold's crossover is in the midrange - 1000hz.
The tweeter and base are aligned with the crossover and physical position such that at the cross over point the tweeter and base are perfectly in sync with both phase and time - hence the name "dual concentric".  Unlike other dual concentric drivers, this phase coherency at the crossover is the key to the Tannoy sound.

If you use different amplifiers for the tweeter and base, they will have different time constants and you will destroy the phase coherence at the crossover point. You will defeat the whole purpose of the Tannoy design.

You should stick to one amp, unless you want to try the same amps top and bottom.

Personally on my 15" Monitor Golds ( Belvedere Seniors & GRF Professionals ) I prefer high power solid state to tubes as the Tannoy drivers are medium efficiency, as you increase volume they soak up more power at an increasing rate.

First Watt amps voiced with Tannoy, probably the best amp for them if you want killer SS amp.

If you are into having a really expensive, really cool looking system that soaks up money and space far out of all proportion to how good it sounds, you could scarcely dream of a better method than bi-amping. Bi-wiring is for chumps. EQ? Spare me. Bi-amping rules. 

In truth only one thing beats bi-amping. Tri-amping. Be sure to use mono-blocks. Preferably with outboard power supplies. Because as everyone knows the more boxes and wires the better it sounds.