Proac Response 2.5 and subwoofer ?

I use a pair of North Creek Music Borealis speakers, which are, to a large degree, a clone of the Proacs. I recently added a relatively low-priced M&K sub before they went out of business. For me there was a measureable improvement in the sound, or at least in my enjoyment of teh sound. The rest of my system is pretty solid...Classe, Sonic Frontiers and modified Rotel cdp. The addition of the sub did just what I had hoped it would....solidified the bottom end and gave me a better overall balance.

Oh. sorry not to answer your question, but in my situation, I first used a Onkyo home theater powered sub and when I found postive results I went to the Cambridge Sound Works ones.

I say that if you are happy with the Sony, go with it, using a better quality sub, I have found is not always fool proof. In another system of mine, I used a REL Storm III and felt it had a negative on the over sound of my Micheal Green Chameleon Speakers which are floorstanding full range.

some people here may come to your home and take your audiophile license for this...but yes, I had the same experience with Acoustic Energy Ae2s and a single, then a pair of Cambridge Soundworks subs. I wanted to it to sound bad, but to my surprise I enjoyed it.