Topic: Hiss from front panel input


I am having a problem with hiss in one of the front panel inputs of my FF800. I've been using the front panel input 8 with the TRS connector without problems until I connected a microphone with phantom power to the XLR connector of the same input. After that, the front panel input 8 started go generate a lot of hiss. With gain pot at +10 db and no cable connected, input 8 level meter shows -83db, while other inputs have -109db. With gain pot to +35db, the input level is about -53db compared to-99db of other inputs.
I don't get any hiss if I enable only the back panel input 8, neither if I use front panel input 7 (which from the schematics uses the same ADC as input 8).

Any ideas what could have happened? Could it be that some component have been damaged from connecting/disconnecting the cables?