Hey.

I have a faulty Audio4+ with the same symptoms. Actually this is my second unit since the first one became silent after a few months (it looks like it’s ok but no audio comes out of it) so the guys at iC sold me a refurbished second one for half the price as it would be too expensive to send it from Brazil to Canada and back paying the abusive electronics custom taxes in my country. It was a few years ago.

But now my second one has the same problems you have mentioned (VERY low preamp levels and digital distortion if I increase the gain or the input signal). Other than that the unit works, but preamps are doomed.

So I had an electronics technician investigating and he told me the problem is with the DAC chip, which also controls a lot of stuff on the preamps. The part number / code is AK4627 but it is very hard to get it as he could only find them at a Chinese dealer called TABAO but the website is in Chinese mandarin only and they won’t ship it to Brazil.

Anyway unfortunately I guess i’m giving up on these Audio4+ since in my experience they are not reliable and I cannot justify to myself getting a third unit. I love to be able to have it connected to my iPad and Mac at the same time but I can’t waste more money on things I cannot repair living in Brazil.

I just wanted to post about this DAC info and my experience since I have seen other posts in foruns about this preamp gain/ distortion / low volume on these units but nobody ever replies or has any clues about what is going on and it seems this DAC chip is the culprit. I suspect that leaving the unit on all the time (it gets very hot) and / or electricity instabilities in my house may have shortened its life. Who knows.