Looks like this is a post from a while back, but I've searched and can find no other posts referencing this. I have noticed the exact same issue with reverse delay. At each repeat of the delay cycle, there is a definite "click". Just like OP, I have tried moving the delay to different points in the chain, changing the mix parameter, note/time, and feedback, and it is always there (changing the time parameter just changes how often the click happens). Just like OP, I can duplicate this every time just by playing a chord that sustains longer than the delay time (to really make it obvious, do a volume swell). To further troubleshoot I plugged in an old Boss DD-6 into the FX loop on the Firehawk and set the DD-6 up in Reverse mode and there is no click - the reverse delay works just like I think it should. Firmware version is 1.20.00. I am also using Headphones to monitor sound. I'd really like to find a fix for the problem.
Anyone out there have the same issue?
