I used one of these 25 wpc in a room bigger than yours:
http://archive.anthemav.com/OldSitev1/review/int-1.html
http://archive.anthemav.com/OldSitev1/review/int-1.html
How many tube watts for Vandersteen 2's?
In an 8 x 12 room for jazz, female vocalists at moderate volumes how many watts? Is a VTL IT-85 enough, I'm using a YBA Integre right now and it seems okay but I would like to try tubes