If you're needing the DAC just for listening to music, I'd recommend you look at the iBasso D1 from www.iBasso.com
. There's a long thread on this amp in the Headphone Amps forum. The D1 has great sound through it's own headphone amp, or it can act as a stand-alone DAC and connect by miniplug interconnect to the headphone amp of your choice. You can hook up your laptop to the D1 with the provided USB cable, then use a miniplug cable to connect from the AUX Out of the D1 to your headphone amp (or powered speakers). Or, you can just connect your headphones to the headphone jack of the D1.
The D1 is bulkier than the 1st Gen iPod, but if portability is not an issue, I've been very happy with the D1 for listening to CDs, FLACs, ALAC and MP3s from my PowerBook. You'll connect to the D1 via USB or optical digital out.
Another DAC/Amp solution with rave reviews is the Corda Move. It also has a huge following on the Headphone Amps forum. It'll connect to your laptop via USB only, is more portable than the D1, and supposedly has better sound than the D1 stock (D1s are still too new to have extensive burn in).
The Move does not have a line out so you'll have to use it as a DAC/Amp combo. If you like the amp section of the D1, however, you have a swiss army knife of amps, and you can sell your current amp on the Head-Fi forum or ebay.
Both amps, however, will cost you over $200. The iBasso D1 cost $252 after shipping, the Move will be close to that. If you're interested in the Move, check out Head-Fi Sponsors Meier Audio or Todd the Vinyl Junkie. For the iBasso, check out www.ibasso.com
Both the D1 and Move come with the cables you need to connect to your laptop. The Move, however, does not come with a battery or AC adaptor, but does come with an analog mini plug interconnect. The D1 comes with a bunch of cables, but I had to get a miniplug to TOS optical cable ($16) to hook up my iriver. The D1 does not come with a mini to mini interconnect. Neither come with an iPod line out dock. You'll have to factor all that into the final cost.
Owners of both the Move and D1 have been very happy with their respective amps in terms of sound quality and build quality. However, this being Head-Fi, most owners seem to own multiple amps.
If you want a size comparison of your amp and the D1 and Move, enter the dimensions in www.sizeasy.com
Another thing to consider if you're going to travel: you can replace the battery of the Move with an included tool; but with the D1 you'll have to carry the small universal AC adaptor to charge the built-in rechargeable batteries.
Hope this helps.