impedance match of preamp and main amp.

I like big solid state, biased hard into class A with huge power supplies, and that has bi-polar output for great current delivery.

The Classe CA400 you have is no slouch either, I would be quite happy owning that even though they are Mosfet output.

Your Vk 51se should be happy into that 75kohm input impedance.

The B&W 800D's are a bit of a bitch to drive, if you can understand the test here.
http://www.stereophile.com/content/bampw-800-diamond-loudspeaker-measurements

I would be more likely to go the big class A bi-polars for these 800's like what I use. Things like the big high class A biased Krells, Mark Levinson's and such that use bi-polar output stages, for good current delivery for the 800's.

Cheers George

This thread has real good stuff / discussion . It helps me understand the application of "Ratio" better now - there is more to it than simple 1:10 min. . Thanks Georgelofi , Mapman , Almarg .

Changing the coupling caps in the preamp may not be the best move. The bigger the coupling cap, the more coloration it can impose at frequencies well away from the cutoff frequency. For this reason coupling caps are often made as small as possible while still retaining some ability to drive lower impedances.

We got around the problem by having a direct coupled output.