Does input impedance depends on DC voltage?

[yeeshkul]

Someone has told me that he can hear the bypass tone suck of non-true bypass pedals differently when he uses battery and 9V adapter. Is that possible? DC between a new battery and stabilized 9V wall-wart can vary for circa 1V. Is that 1V enough to change the pedal input impedance so we can hear an audible difference in tonesuck (bypassed pedal)?

[R.G.]

Someone has told me that he can hear the bypass tone suck of non-true bypass pedals differently when he uses battery and 9V adapter. Is that possible?

Yes.

DC between a new battery and stabilized 9V wall-wart can vary for circa 1V. Is that 1V enough to change the pedal input impedance so we can hear an audible difference in tonesuck (bypassed pedal)?

Your question then is - how can he do that? There are several ways.
1. There are many different 9V adapters. It is possible that the adapter that he once tried this with an adapter that produced something different - sub-audible hiss/noise, ripple, etc. - and heard a difference; thereafter he simply decided that there was a difference he could hear, even if other people could not, and did, in fact hear the difference, in his mind if nowhere else. The human mind can do things like this. Notice that to the mind that has this preset idea, the effect is *real* - they really do hear a difference. But the difference can sometimes be added somewhere between their ears and consciousness, not necessarily in the sound vibrations coming into the ear.
2. There are different buffers. Simple emitter follower buffers might do something like this under some conditions. As noted in (1), it only has to happen once for a human mind to take it and run with it. Well designed opamp buffers are remarkably resistant to power supply changes, so there are some buffers that probably would not really do this.

[yeeshkul]

Thanks RG.