Whatjd - if you just want to get your feet wet - take a look at ...
- Musical Fidelity V90 DAC
- http://www.needledoctor.com/Musical-Fidelity-V90-DAC
- 1x RCA coaxial connector SPDIF 32-192 kbps (16-24 bit stereo PCM)
- 2x TOSLINK optical connector 32-96 kbps (16-24 bit stereo PCM)
- 1x USB type ‘B’ connector - Asynchronous data stream at up to 24-bit/96kHz (Determined by source file/computer settings)
- 1x 12v 500mA DC power supply
This will get you very good quality sound that you can tweak to make even better
You won't require it's USB interface if using it with your CD player, but you can use it to get "acquainted" with all the issues and grow
The thing I like about this unit is - the power is 12volt DC - so if you want to tweak the power supply to the max - you can simply use a 12 v battery
It also has one of the best USB interfaces in a budget DAC and the rest of the circuitry is pretty darn good also.
$299 gets you off to the races really quickly
I'll add another vote for the Bifrost - but then you are getting up there in price.
However, you can tweak it to provide excellent performance - even the 4490 version sounds extremely good.
Your Choice - good luck :-)