Originally Posted by mikeaj
Well it can be, with respect to a given device. It's a very well-understood phenomenon easily explained by examining the circuit. If the voltage to a certain system is too high or low, the value will be clipped when passing through. It's how electronics work. In some systems, circuits are used to intentionally clip inputs to certain levels, if clipping is needed for some reason.
However, the rest of your sentence doesn't really make sense to me. What we're interested in is the output voltage level of the source, and whether the amp can handle it. For amps, it's more common that you could run into clipping from the gain being too high or the output not being strong enough, but it's also possible for an amp to clip an input voltage that's too high for it to handle—no matter what the volume is set to.
You're right that improperly-set EQ can easily lead to digital clipping though, and that's common.
I'm not an electronics expert, so that explanation will work for me. As for a clarification of the rest: while the first part was about (apparently misunderstood) electronics, the second was simply a list of practical reasons I have experienced distortion and/or clipping myself:
Usually, if the volume control was set relatively low on the amp, yet the actual volume in the headphones was relatively high and clipped/distorted, it was because somewhere along the input chain the signal got over-amplified, whether through the overall source system volume, or in combination with a high separate player software volume and/or EQing (even flat), or a mismatched gain setting, or, I guess, that voltage difference.
I still think that by keeping the source volume at an appropriate level, he should be able to continue using his combo without clipping even if there is a voltage difference. After all it only gets clipped when going past a certain limit, so if one keeps it below that by controlling the source volume, it should be OK.
(Which, after re-reading your other post, you pretty much wrote as well: "By the way, if it really is clipping, all you'd have to do is lower the volume on the computer slightly")
Edited by TheGrumpyOldMan - 4/13/12 at 11:11pm