Hello, my name is Jacopo and I'm the owner of a Fireface UFX interface.
Yesterday, while using my UFX I noticed a strange behavior of the Mic 9 preamp. When I try to increase the gain (either using Total Mix or the unit's encoder) there seems to be a delay between my gain increase command and its execution.
Sometimes, some seconds after my command, I can hear a "pop", and then the preamp reach the desired gain by itself.
Sometimes nothing happens after my command and I have to produce some sort of transient in front of the microphone plugged into the Mic 9 input to "unjam" it. After the transient I can hear the usual "pop" and the preamp starts to work at the desired gain.
Microphone channels 10, 11 and 12 seem to be unaffected.
What could the problem be?
I hope it doesn't require another trip to Germany, because it just came back after a power supply malfunction.
Thank you very much.
Best regards,
Jacopo

Edit: the issue seems to occur only when the interface is connected to my MacBook Pro, not in stand-alone mode. Channels 10, 11, and 12 are affected too.
Could it have something to do with the recent upgrade to Mavericks?