Except according to the QSG (and @Roblof ,) it shares some characteristics with the X32 in terms of the TRS AuxOuts; they have 5dB less headroom than the XLR outs (16dBu vs 21dBu.) Compare this to the TRS AuxOuts on the M32 line, which go up to +21dBu, the same as their XLR counterparts.
Yes forgot that small difference. But I wouldn't consider that a difference in sound quality (which was the OP initial question). Rather that would be a difference in levels. As I mentioned when I first beta tested the MR18 with a band that I had been using the XR18, that the difference I heard was like the difference between silk and standard bedsheets (smooth and luxurious).
Unfortunately I have not had an opportunity of trying the Wing in a live event yet. I had one lined up with another sound engineer. But because of the lack of mixing app, he decided to do it with his M32.
With no input terminated and that type of noise on the output I do not think there will be any quick field fix. I suggest you start an RA with service and they can guide you through the process of getting it repaired.
We experienced exactly the same problem last night with the X18 air as is being reported....worked perfectly until the concert hall filled up with people (on their phones) and the Ipad lost connectivity with the desk...no matter what we did no connection..
A few times we got an authetication error.....this is a BAD problem BEHRINGER !!!!!!....VERY emabarrasing.
If you had done your research, you would have seen that we've been telling everyone since the X-Air was released to use an external dual band wifi router for any live events.