The TAD, with its beryllium drivers, is more forward than the Rockport, which mostly uses warm-sounding Audio Technology drivers (its tweeter is also beryllium). The MM3's is more neutral, its character falling in between the two.
The MM3's have a huge advantage with their powered, equalized sealed-box subwoofers, allowing them to be dialed in precisely and to work in a much larger number of rooms. I'm not dissing Rockports, which I think are tremendously good in terms of overall sound and build quality - it's just much tougher to dial in a ported speaker with 15" bass drivers. And the MM3's are at least as good as the Rockport in all other frequencies, can be dialed in, and can be driven with no feedback, lower powered amps because of the powered woofers, which is another real advantage.
Disclaimer: I own MM2's, but I've heard a lot of Rockports and a couple of pairs of TAD's.
The MM3's have a huge advantage with their powered, equalized sealed-box subwoofers, allowing them to be dialed in precisely and to work in a much larger number of rooms. I'm not dissing Rockports, which I think are tremendously good in terms of overall sound and build quality - it's just much tougher to dial in a ported speaker with 15" bass drivers. And the MM3's are at least as good as the Rockport in all other frequencies, can be dialed in, and can be driven with no feedback, lower powered amps because of the powered woofers, which is another real advantage.
Disclaimer: I own MM2's, but I've heard a lot of Rockports and a couple of pairs of TAD's.