Hello All, was reading this thread while narrowing my choices for a new sub and thought I'd pitch in my 2 cents while I've got the subs at home. I'm in the market for a sub that is very musical, fast, reaches down low, and is useable up to around 100hz to match with my Def. Tech. Pro Monitor 1000's and Procenter 2000. Listened to a couple Velodyne subs (better one was the SPL12) in the store, wasn't impressed. Typical Velodyne sound (IMHO), lots of air movement but not very transparent sounding. Spent some time with the Monitor Audio SR-W12 in the store, and while it sounded pretty good it also sounded like it's frequency response curve looks; much higher output on the top end. While I was there I heard a Paradigm Ultracube 12 who's bottom end output was crazy, but not well suited to my needs. Then went to Magnolia AV in Lynnwood to listen to the Definitive Technology Supercube II, the Martin Logan Abyss, and something comparable from REL's T-series. I was highly impressed with both the ML Abyss and the Supercube, not that I had anything against the RELs, they just weren't really available like the other two. Couldn't decide in the store, so I took them both home to audition, and here I sit now. Been spending as much time as I can with both of them over the past week and a half, and I am still torn. Both are very musical, very flat frequency response curves, both reach plenty deep (the Abyss more so) and both are very transparent. I am in a condo so I haven't been able to open the taps entirely, but from what I've found the Supercube will run out of headroom on very demanding tracks such as track 4 on Pomp & Pipes where there is deep powerfull organ pedaling happening and the big powerfull bass drum kicks in; the abyss will hit that drum and you feel the room drop whereas the drum gets lost with the Supercube. At lower volumes this isn't an issue. I'm looking forward to taking both subs to a friend's house where I can really find their volume limits. The other big difference I'm finding is that the Abyss tends to sound a little fuller where the Supercube has a little crisper sound to it and blends with my satellites a touch better. Lastly, I feel that the Abyss does a better job pulling information out of tricky bass lines, very quick bass hits and quick plucking of bass guitar strings. I suspect that all these differences have to do with the Subs' designs; the Abyss having a 12" driver powered by a 300w amp in a sealed enclosure with the Supercube having an 8" driver and 2 passive radiators (also 8" ea.) powered by a 1200w amp. I've been throwing everything at these subs; Yo-Yo Ma and Orchestral music and big pipe organ stuff like Pomp & Pipes and the opening to the Phantom of the Opera, Santana, rock like Metallica, Slipknot, Disturbed etc. As it stands, I am undecided but leaning slightly toward the Abyss with the idea that as my system continues to be upgraded I will eventually have a set of main speakers that reach a little lower and will tighten up the upper base, and one day I'll have a basement where I'll really be able to open the taps on the Abyss! I wish I had a chance to compare these two to the ML Grotto i, so if anyone has done this comparison I'd love to hear about it. On a side note, I would call my room rather large as it's approx. 12' x 24' with 13' ceiling, and is open to the hall and kitchen. One last comment, the Abyss handled the scene in Hellboy II where the stone giant awakens from the earth more cleanly than the Supercube, and gave a greater portrayal of sub-bass in the LFE track. Hope this review helps somebody!