We lost a channel on our DM48 last week, It was a channel we used regularly with an condenser instrument mic (DPA 4099), but as we were setting up the other day, no output on the channel using either a DI, Dynamic or condenser mic (48v on or off). we do hear a regular but very faint clicking noise which is also evident in the input meters. have lost channels/preamps been an issue with other users?