When I Overbridge enable my new A4 I get a screaming noise from the main outputs, the level of which is directly controlled by the master volume knob.
I am on a Win 10, 64bit desktop PC. My soundcard is an RME babyface.
I am running the latest A4 firmware (1.23C) and the latest Overbridge software (1.10.1).
The Overbridge control panel recognises my A4 and I can open up the A4 as a VST inside Live.
I have changed the cable, changed the USB port (tried USB 1, 2, and 3 ports) and have disconnected every other USB device from my computer. I have cleanly installed Overbridge 3 times, following the installation instructions to the letter. I have disconnected my computer from the internet. All to no avail. Every other USB device on my computer works fine (including a Virus TI).
When not Overbridge enabled, the A4 works fine. Any suggestions or should I raise a support ticket?
Try the options from this thread on the AR
Sounds great! is it a digital type of screaming?
Not ‘warm’ or ‘rounded’ or ‘organic’ or ‘moogy’
I may have to buy another if so
Mine did the same… im on windows 10 and Im guessing you are too.
Anyways turn off your speakers first… turn on overbridge mode on the a4. Start the overbridge program and youll see the VU meters are maxxed out on the channels making the noise.
Theres a toggle switch beneath these meters in the software. Turn them off (im typing this from my phone in bed so am typing this from memory). Then click apply. Turn them back on and hit apply again. Now turn on speakers and viola… fixed 
Thanks KJ (and hotscience), that did the trick.
Fortunately I always have all my levels down when I switch on equipment and when I install new gear.
I think Elektron should look into this issue as it is something which should not happen (or edit the Overbridge install instructions to advise of the possibility of this issue and what to do to overcome it).
Yeah it nearly blew my speakers when it happened first time round … almost wish it had now as I have my eyes on a set of Genelecs and that would have been the deciding blow to pull the trigger on them 