@brunomarcs The buyer has sent a video of the crackling noise and now says that's gone. Now the volume is making a noise. I've offered to refund him but he wants to send it schiit for repair.
I would offer to take it back again and if he still wants to send it to Schiit for repair, then that is on him. As for the volume making noise, it does. Is it coming over the speakers or just the relay clicking?