My pedalboard has 11 pedals on it, and 5 before the delay have for the past year been making really loud pops when I pressed the bypass footswitches. The delay then repeated these loud pops in all their annoying glory.
So, I tried the Lehle DC Filter.
I tried it in every position, some even on the pedalboard. ;)
No matter where I placed it, nothing seemed to help stop/reduce the popping. But in some positions it did manage to cause some strange and loud sounds that I have never heard through a guitar amp before. (In one position it made clicking sounds like The Predator, I kid you not!).
Because I knew I had Thomann's 30 Day Return Policy, I decided to place the Lehle last on my board (the cable from my amp is plugged into the Lehle) in the hope it might just reduce the popping a little bit.
After about 5-7 days, I noticed the popping volume had reduced significantly, and sometimes did not happen at all.
So, I decided to keep the Lehle, as it was clearly doing something to help.
After another couple of weeks I noticed the popping was pretty much gone. Once in a while I might hear a very faint pop in the delay repeats when I press a footswitch, but it is VERY faint and I have to listen closely for it.
So, it seems to work, but it did not work straight away for me.
I would tentatively rate it at 5 Stars.
It seems to be doing what I wanted, it doesn't require power, and the build quality is solid.
Assuming I'm allowed to Edit my Reviews, I will report back if the popping ever returns. (I would feel a right wally if the stop of the pops actually had nothing to do with the Lehle).