What should I upgrade

Try finding a used integrated like an ARC, Prima Luna etc.

+1 to Hifigeek1's reco, look for a nice tubed integrated amp in your price range.

What kind of speaker cables and IC's you using.
You have to go a long way to beat those Silverlines.

Thanks for the responses. I know that the Silverlines are going to be hard to beat without spending a whole lot more money, where I have to have them, anyway. I noted above that those were here to stay for a while. I only mentioned them for the sake of speculated system synergy.

I have been giving some thought to grabbing a tubed pre amp, but then also thought that my cheapie DAC might need upgrading. I wasn't sure, so posted this thread for some opinions.

I am a bang for the buck kind of guy, so I run all Blue Jeans cabling.

If you really like your system, perhaps you can just enjoy the music and not tinker with it - human beings have this psychological need to venture out and experience something new, and this can get costly in hifi real fast.

You know about the law of diminishing returns - higher you go, the less satisfying will be your returns, unless you spend much much more...

What I did, when i got the itch, is to get a new mini system for a different part of the apartment - gym area, kitchen, bed rooms, etc.

If you want to go this rout, might be interested in something like this - it has computer streaming capability + improves ipod sounds by using it's upgraded DAC on play back.

http://www.accessories4less.com/make-a-store/item/TEACH013BA/TEAC-H01.3-B-Digital-Streaming-Micro-System-Black/1.html