Q: I llove my Line 6 M13, but I can’t really tell the difference between true bypass and DSP bypass. What’s the difference?
A: In true bypass, the analog signal entering the M13 (or M9, if you have one of those) is passed straight to the outputs, without being converted to digital and without being buffered. With DSP bypass, the signal is converted to digital even when the effects are bypassed. Aurally, both offer excellent sound quality — some users hear a difference and prefer one over the other, some don’t.
There is one functional difference: in true bypass, delay repeats or a reverb tail will be cut off if you bypass while the delay is trailing away. With DSP bypass, delay repeats or a reverb tail will continue sounding after you bypass.