Mapman,
I don't know how easy the Triangle speaker is to drive, but, I do like how it sounds. It is a nice and lively speaker that has a somewhat "bright" top end that is not harsh or hard or sibilant--a VERY hard trick to pull off and something I find quite appealing. Maybe not a 45 SET, but certainly there are other candidates that would easily match with the Titus.
Also, I am not one that is completely wedded to SET amps; I own both SET and pushpull amps and like both types. If I had to pick a single favorite amp, it probably would be a custom-built OTL that a friend owns that makes almost everything else sound dead in a direct comparison. I heard it in a direct comparison with an Audio Note Kageki (the SET ajmp I own) and the OTL trounced the SET in the short-term audition of the two. If I owned a Titus, I would at least be tempted to try an OTL, even though the Titus really doesn't need something extra to bring it to life.
Charles,
I agree with you that digital sources can sound terrific. If I had to choose digital or analogue, it would be digital because there is MUCH more available digitally than on vinyl or tape. Most of my listening is from CDs (ripped to a server). However, while it is not an issue of the inherent capabilities of the medium, there are lots of digital reissues of analogue-sourced music that is quite poor and it is striking how much better an early issue on vinyl sounds compared to the digital reissue. This might have to do with deterioration of the original tape, but, most often it is indifference in the mastering (evidenced by very good digital reissues of the same music by specialty houses like Mobile Fidelity). Most jazz digital reissues are quite good, and some classical digital reissues are actually better than the analogue originals (e.g., 1970-80's DG recordings that were poorly mastered for vinyl), but, there is a LOT of reissued pop and rock that is terrible sounding in the digital format. That is why I have both formats even though most of my listening is from digital sources.