If you are committed to the existing files, don't spend too much money else you will start to cringe at the defects in the .mp3 files that a good piece of equipment will reveal. try a Fubar 2 USB dac for $137 and see if that doesn't float your boat. I have a Fubar 3 (includes a headphone amp) that I use at my computer with FLAC and 320k mp3 files and it does a great job.
As an alternative, you can always pay a ripping service to redo all your CDs ($.25-.75 per disk, depending on service). At that point, you can use any digital solution you want and never worry about quality. It's well worth it in the long run.
As an alternative, you can always pay a ripping service to redo all your CDs ($.25-.75 per disk, depending on service). At that point, you can use any digital solution you want and never worry about quality. It's well worth it in the long run.