Currently, I used IV and my amp is Rowland2. My room is almost the same size like you. In my opnion, Rowland do a good job in overall performance including the bass. However, I don't quite sure how much bass you want since you play some A/V. If you not too hunger, the Rowland 2 can be the choice, while consider the used price at around 2.5 KUS$.
Another choice try a little old amp but bass not disappoint you for sure. Krell KSA250. I think used price less than 2K.
Another choice try a little old amp but bass not disappoint you for sure. Krell KSA250. I think used price less than 2K.