I have the new S3X-H's. They are WAY better than the old 3's which I also had. I also have the S5A MKll's which were way better than the 5A's. The difference? The round midrange added in both is the key. Those ribbons just don't cut it by themselves in the midrange. Klaus figured that out a couple of years ago with the 5's and upgraded them. He just did the same thing with the 3X's. There is a remarkable difference. There are other major improvements in the low-end and the ribbon tweet too. This is a completely different speaker. For those who accused, including myself, the 3's of being not quite there, that day is over. The "presence" is dead on with these. Although it may appear they are a bit center focused compared to the old 3's they're not. They're now actually right, hence why Klaus changed them. The power is way better too, can't bottom them out, at least I haven't yet. The best thing however, and where it counts most, is they play beautifully at very very low volumes too.
Because the S3 fad has come and gone these are sleepers right now. The only reason I tried them was because I saw he'd done the same thing to the these he had done to the 5's. That intrigued me. However I wasn't quite ready for what I heard nor was I ready to shell out the cash BUT these things are amazing! Between these, the 5A's, and the NS10's with the Bryston, I'm covered now. In fact just these would do. Check them out if you're in the market for new monitors. I had the MM27's in here a few months ago and I sent them back. These new S3X's are way better for my situation. They just sound "right" now. No wonder Michael, Armando and several others were/are freaking out over these new ADAM's. This is the way they should have been in the first place. At least Klaus had enough sense, drive, and humbleness, to know he could better them. That's what a good scientist does though.
YMMV but I doubt it.
Oh yea, forget the sub, will not be required period...