Unison Research Preludio or Sinfonia for Tannoys?

Dear Friends,

I use a pair of Tannoy Turnberry SE speakers and after trying many many amps, I keep coming back to SETs. This time I want to try a higher powered single ended amp. The Unison Research Preludio and Sinfonia looks like having decent usable power for the Tannoys. I would love to go for Sinfonia for its higher power but it also has a lot higher negative feedback (14db) and lower bandwidth at the output transformer than the Preludio. Any pointers on these 2 amps will greatly help my decision making