Jaxx,
I've listened to alot of music on the 6T's without the subwoofer now, as well as to Star Wars Episode II. I was impressed at how good the 6T's sound without a subwoofer. Bass is tight and surprisingly low-reaching-- the LFE effects in Episode II were pretty good through the 6T's. It still sounded better with the subwoofer, but I doubt it reaches a whole lot lower than the 6T's. My subwoofer was a PSB Century Subsonic 2i which doesn't reach particularly low.
The good news is, PSB is going to fix my subwoofer for free! Wow! Even though it is two years out of warranty. I am very impressed. Still waiting for replacement amp and power supply unit-- but they have no responsibility to fix it for free and still they are doing it. Very impressive indeed.