I have just been totally amazed. Singular Sound support just got in contact with me and they are going to replace the unit!!!
Outstanding. Huge kudos to them and it’s a first for me, that company support is going over and above. Mucho appreciated!
Don’t know if my ‘noise’ issue is relevant, but I’ll toss it out…
I have an older Carvin AG100D which I am using as an amp for acoustic guitar and the BB. When the BB was plugged into Ch2 of the Carvin a noise like you described would start and seemed to build to some maximum amount. Channels 1 and 3 on the amp didn’t do this, but the electronics on those inputs was slightly different also. After futzing around a bit trying a few different things I believed it was sort of a problem with the design of the Ch2 input. Later versions of this amp had a ‘dampening’ circuit between the jack and the first stage OP amp which I think was added to suppress a ‘parasitic oscillation’. I added the resistors and caps to my older amp to bring it up the more recent version design. This addition pretty much killed the noise I was hearing. Not sure if it was a parasitic oscillation or could be attributed to something else. Have not noticed any noise from the headphone jack using just the the power adapter connected. The output impedance of the BB is stated to be 26 ohms in the specs. I don’t know if this is particularly low compared to my other gear or not, but none of the other gear ever had a problem on the Ch2 of the Carvin amp.
While you shouldn’t have the problem you have it might be worth a try to put a DI box between the BB and your amp to see if that changes what you hear. Pax what are you using for an amp when you hear this?
Another thing to try might be a clamp on ferrite filter on the cable from the power adapter to the BB.
https://www.amazon.com/stardrift-10-Pack-Diameter-Ferrite-Suppressor/dp/B015RAZTIA/ref=sr_1_2?s=industrial&ie=UTF8&qid=1505839817&sr=1-2&keywords=ferrite filter
Just saw your post about replacement. Good luck!!
Unit is now on its way back to the USA…will post an update when replacement unit arrives. Thanks again to all for your assistance, much appreciated 
Noise issues is gone with the new unit yay!! I posted a separate thread re Singular Sound, but again here, I repeat a HUGE thanks to them for going well above and beyond what was required and expected
Awesome news