Taking all of this into consideration (And this goes out to everyone) what are your recommendations for a tube pre for this setup.
Given the reasonably high input impedance of your amps, even if that value is only half of the specified 75K when they are used in bridged mode (which is very conceivable), and their slightly above average gain, you have a very wide range of possibilities. Given that the sensitivity of your speakers is also somewhat above average (apparently specified as 95 db/1 watt/1 meter) I would just suggest avoiding line stages having highish gains, above say 10 or 12 db or so. Especially if you are using digital sources.
Good luck. Regards,
-- Al