I would also recommend the Taddeo Digital Antidote II. More information can be found here:
www.taddeodigital.com
It is inexpensive, and does an impressive job of correcting the phase timing errors that are present in 16/44 digital, which seem to be largely responsible for the tiring edgyness that digital is known for. I have just received a unit, and consider it a worthy upgrade, especially considering the more than reasonable price. The sound of my Rega Jupiter 2000, while great without it, is certainly more full-bodied, smoother and warmer (as well as sounding harmonically more complex, more similar to my analog set-up, which gives the impression of a higher resolution source).
Pretty well no matter what you do to tweak, you will still have the lingering phase problems, I think Taddeo is the only company to actually address the problem. With a 30 day guarantee, it is difficult to lose.
