But you can upgrade your processor to make your music sound much more as if it were live, and it doesn’t take any soldering. Just plug an undistinguished box called an outboard DAC between your digital music player (like an iPod, CD player or computer) and an amplifier. (The devices use a USB, optical, 30-pin or coaxial cable or RCA connector cable.) It does better math to make better sound.

They can cost more than $15,000, though some are only $100.

But spending a lot of money won’t necessarily guarantee better sound. Any sound system is only as good as its weakest link, so a $500 DAC isn’t likely to improve a really rudimentary receiver. And because of variances when you mix audio components, a specific DAC may sound very different in your system than in your buddy’s.

Despite all those caveats, it’s not hopeless. After hours of testing several DACs on my 30-year-old home hi-fi and many more hours in a modern high-end system at Soundscape, an audio store in Baltimore, a rotating listening panel of employees and customers came to as close as a consensus as you’ll find among audio buffs. We listened to a stereo wired so we could switch between an $1,800 CD player and a computer playing the same song using a DAC. We also listened to the song on the computer without the DAC. The listeners didn’t know which they were hearing.

Though we mostly listened to a variety of music converted to the Apple lossless format, which makes files smaller but preserves fidelity, we also tried out some MP3 files, which are lower fidelity but take up less space in a player.

We had previously tested low-priced DACs and were disappointed. We found that several costing around $350 provided the best value.