Threshold T400 bridge or bi-amp?

I just bought a pair of Threshold T400 and I am wondering which is the best way to go between bridged them or using them in a bi-amp configuration. My speakers are B&W 801 S3 Matrix (4 ohms) and the room is about 15' by 25' with cathedral ceiling.
I am going to start driving them with my Wadia 27 but I am thinking on buying a T2 preamp. Any advise on this? By the way, I know the input sensitivity for the single ended connection is 1.4 volts. Does anybody know what is for the balanced connection? The manual does not specify anything for balance.

Altho I might not be able to give you a direct ans, here are my thoughts as a prev. B&W owner:
The B&Ws require a lot (& I mean a lot) of power esp. current to make them sing. You probably have already noticed this? Just when you think you have them jamming & you add additional power, they just get better! I have a friend that drives his N803 w/ a Plinius SA-250. He found that the SA-100 or SA-102 to be inadequate. Hence I feel that you will benefit slightly more from bridging the T400 & using them as mono blocks. The bridged T400 should be able to wrestle that large woofer to the ground thereby maximizing your listening pleasure.
Of course, just MHO. FWIW.
Thanks for you answer. I own also a pair of N803s and I am driving them with a Threshold S550e (25o watts/ch and 30 amp continuos and 130 peak. They sound so good. Those were the ones giving me the bug to change from my Sonif Frontiers Tube monoblocks back to SS.
You are right about how the 801s like power. When I was auditioning them I listen to them first with a ML 332 (200 watts/ch) sounding very good butn then the dealer change the amp to a ML 333 (300 watts/ch) and WOW!! what a difference. That amp really made them sing and was controlling them at it's pleasure.

The T400 will give me 300 watts/ch in a bi-amp configuration and a big 900 watts per monoblock if bridged.

I have heard that in the bridge mode I may loos some of the bass control becase it loses some in the damping factor and also the soundsatge is not as big and deep. That's the reason I am looking for somebody that already have tried it before.