I reckon I can help a bit LiquidPain ! Since I'm getting a Titanium HD soon, and I've looked through a fair few sound cards in my research. The HD is a newer card compared to the older Titaniums, with uprated DAC's (I think there are two on the card) and better OPAMP's from what I've seen, its a nice piece of kit.
Personally, on my Xonar card, I stayed away from anything like bass boosts, cause it just tends to make it lose clarity, and the bass can become less thumpy with just more of it, its not very nice IMO. Depending on your speakers, if you wanted to add bass, I'd recommend messing with the equalizer instead. Put on a song, and tweak as your playing the song till you find something you like. On my old setup, when I didn't have the ability to adjust like I do on the amp now , I found setting up your EQ much like TC has his done, with possibly a little more added to the lower frequencies helps quite a lot, its personal preference and down to what speakers you run.
A note though, adjusting in your soundcard manufacturers program will allow a much larger adjustment in the freqency than software (Through your music player, for me, iTunes). I find that adjusting in iTunes or the like can just fine tune your sound.
Its all about experiment !
Let me know if you need any more help and I'll do my best to help out