No I haven't heard any mana yet, so I don't know how much improvement the is to be had. I presume the bass tightness would improve? Although I doub't the lower bass volume level would increase, as they won't be able to make the drive unit shift more air, obviously.

I have heard ATC50's on ATC stands in a large room, and they sounded rather good. Better than my recent experience with 100's in a smaller room. They didn't like to be close to room boundaries very much.

Trouble is I want lots of sub bass output, with immense control, at high volume levels. The PMC IB2's seem to be perfect in this respect. The bass volume may even be technically wrong, but I don't care, as it's fun to my ears, with my tunes