Hi Dario,
You need to give us a bit more detail about the problem(s) you've been having for us to be able to help you. You wrote, "spikes, issues, noises".
(1) By "spikes" I assume you mean volume spikes. Is this when switching presets or at other times too?
(2) Issues? What issues specifically?
(3) Noises. Are you saying that you're hearing unexpected noises when playing? This isn't normal, or something I can say we've heard about from other customers. Could you try to isolate the problem to a particular unit?
Generally speaking, if you could describe specific problems you're having with particular pedals (preferably that you can reliably reproduce), we should be able to help you a lot more at that point. Sometimes making a quick cellphone video showing a problem is helpful too.
