I couldn't definitively say its more powerful, but as far as internal soundcards are concerned, the STX was one of the most well regarded cards of its time, so I would guess it might be somewhat better than the Titanium HD (really hedging here, as you can see).
I haven't heard the AD700, so I can't comment on that, but I'd say that the q701 sounds amazing playing shooting games in terms of positional sound (for the games that support it; an example would be the Borderlands series), but its exceptionally loud soundstage does cause the sensation of things sounding further away than usual, which would mean that in CS, the shots fired by other players would actually sound fainter in comparison to, say, the DT880. It is certainly less in-your-face compared to the DT880, I'm guessing here - I can't be sure, but that could be the reason you would find it 'muffled'.
The fact that it doesn't sound any different with a magni however, is interesting. From all I read about the Schitt Magni, my impression was that it was a decent amp; but I'm not sure how it measures up against the one in the Titanium HD. For my own case, going from the STX amp (rather well regarded one as mentioned) to the Littledot MK III made a significant difference in taming the treble spikes, and made the music sound much better to my ears. It was night and day.
The Q701s have a rather unique sound signature imo. It is magical for certain kinds of music, but it is not as all-rounded as my other headphone, the DT880, when listening to multiple genres.
From my own observations, it excels in music with emphasis on vocals, and strings are just magical, while it is not that exceptional for synthesized sounds.