Seems obvious I know but I learned that, again, today. Brought my Strymon Deco to a busy repair shop in London 3 weeks ago because the connectors were crackling, etc and rather than sending it back to the place it was bought at (in Ireland) I went to JPF amplification repair shop in denmark street, London hoping for a quick fix.
The dude being extremely busy didn’t help as he was hard to get a hold of so I called every other day. Finally got a hold of him yesterday and he said "I’m struggling to figure out what’s wrong with your pedal. So I went to the shop today with my cables/headphones, (he tested them as well, they were fine) and we plugged it all… KABOOM, no crackling.
I apologized profusely for wasting his time (he thoroughly checked the unit) and dude said he is happy it’s working, and no charge. He said these pedals are built like tanks, he’s seen many and never had issues with them.
Since then I know that one the 2 sets of cables I was using was faulty. But I am pretty sure I checked everything, all combinations, etc etc.
Well, in any case, Deco works and that’s what matters.
Have a good day.
Also while it was getting repaired, I bought a brand new unit through Amazon, which will now return 
Haha glad it all works though.
It reminds me of making an arse of myself in a pub restaurant. When I got my pie I opened it up to check the chicken was cooked (always do) and it was all pink. I really complained that the chicken was raw. The waiter reminded me that I’d ordered a ham hock pie.
Ahahaha excellent !
But yeah, it’s so often that I locate the source of my problem between my chair and my desk !!
Haha glad it all works though.It reminds me of making an arse of myself in a pub restaurant. When I got my pie I opened it up to check the chicken was cooked (always do) and it was all pink. I really complained that the chicken was raw. The waiter reminded me that I’d ordered a ham hock pie.
haha nice one @artsutanov