Static crackling noise with iDSD Nano DAC

[haizaar]

G'day forum!

I have my good old iFi iDSD Nano that I use about once a year nowadays; otherwise it sits plugged into USB ready to go, but switched off.

Its battery has been long gone, but otherwise it's been working just fine. Today I switched it on and noticed static, crackly noise. It's very pronounced and, of course, disturbing.

I pulled it out of the case. The battery is very "pregnant". I disconnected the batter - didn't help. I powered it from my lab power supply with 4v and indeed it consumes up to 0.2A when playing, but didn't help with the issue either.

The board looks clean - no leaks, oxidation, etc.

The issue is the same both with RCA and 3.5mm jack (can't test digital output though). Happens the same regardless if I plug the USB into phone or computer.

Is there any obvious quick fix to this?

Board pictures are attached

[haizaar]

After giving DAC an off-grid rest for the night, the problem started to reproduce only when plugged into (any) laptop that is connected to my docking station. After bisecting analysis turned out the source of the issue was my recently installer powerline adapter, which caused this static noise even when there was not RJ-45 cable plugged into it. I.e. somehow that noise it generated on the mains managed to to get through dock power supply -> dock itself -> thunderbolt 4 cable -> laptop motherboard -> my DAC.

Go figure....