This is the post, it appears Digitech sent him a replacement and the
new one is fine.
"I just receive my new GSP1101 and I have a strange problem : during 5
minutes starting from the moment I switch on the unit, I get a noise
coming from the left channel of the headphones output. This "parasite
noise" is doing some TIC...TIC..TIC TIC TIC..TIC.....TIC TIC... I only
have this problem with the headphones output and it is not linked with
the output level, I mean, if I turn the output level completly off, the
noise is still there, with same level... The noise is leaving
progressively (lots of "TIC", then less, then after 5 minutes, no
more). It's like the unit has to warmup, then the noise disappear... "