The HDR option was dropped with the Triton, as few people took advantage of the feature (or purchased a HDR-TRI board).
There is no SP/DIF or ADAT optical interface available for the Triton.
If you hate the idea of using the analog line-in on your card (and you would rather use the SP/DIF input), I would suggest getting an exteral AD/DA converter, such as the Midiman Flying Cow (yes that's the real name). Keeping the A to D outside the computer will eliminate all the RF noise that this process creates inside the computer.