TWC - if your are using computer music with an external amp/headphone system, then you are using a soundcard in your computer, either built in to the motherboard, or an PCI card in your computer. There is a DAC in your computer converting the Digital bits to the analog waveform being sent to your amp.
Starting at the beginning though, your computer system is taking the MP3 files from the hard disk and using the MP3 algorithm, converting a highly compressed file format to a digital stream of music, typically 16 bit words with different data corresponding to that fraction of the music. Frequency is 44.1khz (this word length and frequency are the CD standard), so a lot of words are involved.
On this board, it seems to be standard that many folks either get an audiophile quality soundcard (Emu 0404 and up, with other manufacturers too), or choose to have the digital to analog conversion be performed outside the computer box, hoping for better function, and less interference from the computer goings on within the box. So external DACs are considered better than computer cards for this function. That being said, there are internal cards that are probably better than many lower priced external Dacs.
Consider also that your music will sound better with the use of "lossless" file formats. A lot of the music gets lost with the lower number MP3 encoding. As your music system gets better, you can tell the difference in a low quality Mp3, a better quality MP3, and a lossless format (FLAC, or the like).
Many, Many factors to consider from the source to the cans. As you improve the quality of parts of the equation, frequently you find fault with another. Oh the JOY of this forum. Actually, when you hit on a solid improvement, the music itself becomes the reward. Just beware the pain in your back pocket.
