Hi, I'm thinking I'd like to upgrade from one very basic system to another, slightly less basic system. Right now I am running a pair of Sennheiser HD 448s off a Nuforce uDac-2. I'm thinking I'd like to switch to Sennheiser HD 598s running off a Shiite Modi/Magni combo. This upgrade will run me around $400. From what I have read it seems like a worthwhile investment. Would most of you agree? I hope for more than a marginal improvement.