Need Amplifier Recommendations

Personally, I don't think 1 sub will cut it. You should get a pair! I was told by Janis Audio (sub manufacturer) that by crossing over a system at 100hz will effectively quadruple the power to your mains if using powered subs.
I would think that you should try adding subs to your system which you already like to see if that does the trick.

If you can't borrow 2, buy 2 at circuit city and then return them within 30 days.

Thanks for the advice. I have played around with speaker placement and have listened in a near field arrangement as well. The sub idea may be a good idea. I think I know where I can get an AP sub at a decent price. In any event, I also am interested in thoughts on the BAT VK-250 vs. the X-250 with the Virgos.

Thanks again.

(disclaimer, I'm a pass labs dealer)

I've owned the virgo II's and the avanti centuries. I used the virgo's with aleph 2's and the avanti's with an X-350. Adding a big amplifier does change them quite a bit. The bass takes on this iron-fisted quality. More of a change than I hear with most other speakers. The virgo is a good match for the 250 but the 350 may be a consideration if you later buy a large speaker for your room. The 250 should drive the avanti with authority.

That being said I am not sure if the virgo can really fill up a 20x40 roomg. I have a similar sized room and find that smaller speakers tend to become a little too featherweight. They are just not engineered to fill a big room. The trouble you can run into is that the sound may lack a full body because the speaker cabinets are relatively small. In my own system when I upgraded from 8K avanti-centuries to 22K eidolons(now using Quad 989's). In the farfield the Eidolon's had a much fuller and realistic sound. You could sense that a thousand lb+ piano was in the room whereas the avanti's projected a 50lb 'floating keyboad'. The Centuries have fewer bass drivers and considerably less bass than the newer avanti III.

Your room is larger than the AP Luna is spec'd for so you may want to go up a bit. If possible perhaps you could borrow a large amplifer and a big sub to see what really works in your room. Make sure the sub is very fast. AP's sound terrible with lower quality subs.

In discussions with a veteran Audio Physic dealer, he revealed that their designer takes room dimensions very much into account when designing his speakers. Perhaps, it would be wise to consult with your dealer (or the designer) regarding the suitability of the Virgos for the room in which they are now operating. Several previous posts allude to this solution as well.

For what it's worth, I've found that adding a subwoofer in such situations as yours creates more problems than it solves. Attempting to alloy a sub, whose most useful role is to augment the first one or two octaves, to a speaker that is dynamically unsuited to a particular room results in the failure to integrate the bass with the rest of the audible spectrum.