new system/older equipment

I have my music on itunes on a macbook 2.16 ghz laptop. Playing it through an old, cheap ($50) eridol ua-1x dac into an Adcom GFA 523-II power amp and an Adcom GPT-400 amp/tuner combo, playing through Alison 7 speakers. Since I went to the macbook from a good cd player the sound is thin and unsatisfactory. I just added a trial download of Amarra Hi-fi and that helps a bit. I presume that the next thing to do is to replace the old crumby dac with a new one (Dragonfly?). Can anyone make any other suggestions to improve the sound. Other than the Amarra Hi-fi, is there another reasonably priced music player that works with the itunes interface. I've burned most of my cds with Apple lossless, but I could easily reburn them with another codec if there is one that sounds better. I have lots of space left on my hard drive. Thanks -Howard
I have a Macbook Pro with some of my cd's burned onto it with Itunes too. I can't make any suggestions, but I'll be interested in your responses.
your problem is definitely the dac, but you'll need to do better than the Dragonfly. At minimum you could look at the Musical Fidelity Vdac, Cambridge Audio DAC or Moon 100D.

If you burned in Apple Lossless you are fine there. PureMusic works well and is a lot cheaper than Amarra. Cabling (both the USB/Toslink) from the computer to dac, and the interconnects from the DAC to your Adcom pre also make a big difference. Spend a few bucks on some decent ones.
I've gotten really good results with my Lenovo laptop using a NuForce Icon HD USB DAC/headphone amp. It's the same DAC they use in their $1500 CD player and in my system it rocks. It can currently be bought new for around $300 on Amazon or Nuforce also makes a slightly more expensive version that adds S/PDIF inputs (RCA and Toslink) if you need more than just a single USB input.