Proac 2.5 or 3.8?

Given your room size the 3.8s would be a better match--although if you really listen at "moderate levels" the 2.5s would also work. Overall, I think the 3.8 is a more refined speaker and works well with a broader range of music. The 2.5s work best with jazz and rock (my opinion only). The BAT should drive either of them well.

I've owned ProAc 2s, 3.5s, and 3.8s. I have used all these ProAc models in my 28X15X8 room with the 3.8 as being the best sounding. I would go with the 3.8. The 3.8s should sound very good in you room.

My room interesting enough is 26'x17' with 12' vaulted ceiling. My speakers are Proac 2.5's. You mentioned that you are listening at moderate levels, keep in mind as far as I know these are near field speakers where as to get the full benefit of these you are sitting 6 to 8 feet away, if you will be sitting this far away I think the 2.5's will be fine, but if you want to fill the room out a little more when you are not in the sweet spot, I would consider the 3.8's. I liked the size of the 2.5's & thought the 3.8's size might start to dominate the room because of the way that we have it furnished.

I think you need the 3.8's to load that large room. I am a 3.8 owner.

Thanks for everyone that replied. I sounds like both would work but the 3.8's would do a better job filling the room. I will seek out the 3.8's.