I have an MSB Link Dac, and I've done extensive testing with and without my AA DTI Pro. At one time I actually preferred having no DTI and using just a Canare Digiflex cable. Later I realized that the DTI did improve, but
actually it was not an unqualified improvement. What I found was: without, the Dac sounded a little more open, dynamic, exciting. But unfortunately it lacked some subtlety. With the DTI there is more definition and the sound is more interesting -- you don't get bored with it. Unfortunately there is also an issue of the power supply to the DTI. I'm using a custom separate power supply from Monolithic that powers both my Dac and the DTI. And when I compared to a Power Station 3, the Monolothic was definitely the best power source -- I never used a PS2, so not sure.
I'd conclude with: yes, a jitter box does give you the best sound but you have to struggle with all the issues of digital cables, power, etc. and that is a real pain, in the end it was worth it for me but others might want a less complicated life.