Mike, The bass was very good. It is powerful and full bodied up to 500Hz, like a 6SN7 tube built in, then clean and flat above that. Some of my tracks sounded a little too round for me like Rufus Reid on Kenny Barron Live at Bradleys, but other tracks sounded very clear. Classical bass violins sounded full and satisfying, but I know there is a little more detail to be had. If I didn't know what was missing I would be happy with the sound. Carl thought that the bass was better on the Revels than his speakers with dual 6.5" woofers. Nothing sounded dry, if anything leaning toward the warm side for me. But that might have been caused by the rear of the speakers placed only about a foot from the front wall. With a little more space I would expect them open up to sound just about right. Very deep bass like organ music was musically enjoyable, but I only heard one fundamental during the piece. It comes with port bungs so you can easily add a sub. He had a JL 112 sub but we didn't use it.
Also, these speakers are brand new, the dealer said there was only about 15 hours of time on them. Revel recommends 300 hours break in. So the bass will open up a lot more, get deeper and more relaxed. Treble should smooth out more too, but I was happy with the tweeter so more is just gravy.
Someone on Agon forum claimed that the xo uses all aircore coils. Can anyone verify that?
Also, this speaker is a space monster. Ambient cues are well presented to create a strong feeling of recorded space. Carl noted good soundstage height.
