Is it really possible to turn the volume up that high on a computer you're likely to encounter? I've yet to encounter a computer-like device that produces any noticeable distortion on the output when turned up all the way, if the other end has a volume control to make the final output happen at a reasonable level.
Lots of computers I've used allow audio gain to be set above unity, with noticeable distortion as a result. Next time you're in alsamixer on Linux, look at the fourth line down on the top which says "dB gain". It's not uncommon for it to go all the way up to +6 dB or +12 dB, which will almost certainly distort with common source material.
This happens both on my desktop Linux system and my Linux laptop.
Most consumer-hardware I know will have positive gain on the computer output (all built-in audio for my devices, the PCI cards with Ensoniq 1370 or 1371 I used earlier). On the other hand, a lot of the professional audio equipment I know have mixer-applications that has either 0dB as a maximum setting, or clearly labeled 0dB marks/buttons on the mixer application).
You can verify it easily by playing either a 0dB sine-wave mp3 (first google hit: http://www.dr-lex.be/software/testsounds.html) or trying to get a sine-wave test-tone generator. You'll hear the point where distortion kicks in pretty drastic as soon as you reach the clipping level. With a spectrum-analyzer (e.g. FrequenSee on Android) even slight clipping will be very visible (peaks at 3x, 5x, 7x, ... the base frequency will suddenly appear).
