The more I think about it would be just to disconnect the USB when I am done tweaking, certainly for recording. And as its under the desk it is a 2 second jobā¦if I remember. Suspect the high ārfiā will be a reminder ! 
Thanks for all the input peeps.
That bit Toby got me thinking - perhaps itās a Hub issue? what Hub are you using? Did you try going with both POD and AI directly over to your PCās usb ports rather than through hub?
Hi Toby,
Now that youāve looked at Thomann, it might help if you buy a new guitar, a resonator or something? I know almost nothing about this tech thing, but it canāt hurt soā¦ 
(Iāll keep an eye on the thread in case something ever goes hum/sound wrong here 
)
Greetingsā¦
Yeah, Iāll try explaining that one to the missus. Have this high pitched whining so bought a new guitar to fix it. Did it fix ? No !! So maybe I better get another guitar and see if that does. Can we have a bigger house ? No, but we could move to Holland, thereās some one you should meet ! Yes it was his fault.
Limited number of ports on the PC - believe it or not and those on the front are an internal hub as well. The additional Hub for various bits n bobs is a cheap as chips jobbie but works (maybe ) Iād have to spend an hour on the floor, after dragging the amp and PC from under the desk and table to work out whatās going where these days. Its like spaghetti junction behind them but out of sight out of mind ! But Iāll hold that thought, for the future. All is good when the POD not USBed to the PC and that will be good enough for Saturday. Still not settled on the final signal and swapping āpedalsā around and unlike Jason I much prefer a GUI to work with.
I suspect the high-pitched whining might significantly increase with that approach
Cheers,
Keith
Might even reach shrieking levels
Unfortunately for you Toby I believe this might be your main suspect, therefore brace yourself to dedicate an evening or two to dig into your cabling and figure out whatās what 
Surely it canāt be any worse than one of our old data hubs on the campus!
And a zoomed in smaller room 
Well despite what I said in response to Adi, Iāve just got down and dirty to see what was going in USB and Hub wise.
AI was actually plug in to PC USB port direct but I believe the front facia one are like a hub.
Found the Hub that the POD was connected to and rerouted the cable into the front of the PC (as per AI) and still shrieking way. Unplugged the POD and all stopped. So I suspect whatever the interference is (ground loop) is coming from the POD. Not been able to find a grounded PSU adapter, so ordered the HD400 and a couple of patch cables.
Just need to sort out all of the unknown device that have been flagged up while Iāve been yanking cables. Probably my Showtime OBS webcam knowing my luck. 
All of that looks oh so familiar all these years on. Will probably give Keith nightmares,
I have seen worse.
Especially in the old Mercury Distribution Nodes around Westminster when I was a Graduate Engineer: 2 feet thick bundles of black coax weaving their way over the tops endless rows of patch racks for E1 circuits. Every time a new patch was needed, we just threw in another cable.
That was the good old days of the āPlesiochronous Digital Hierarchyā and the āMux Mountainā.
Happy days!
Cheers,
Keith
Not so much plug and play, more tug n lay in those days !
It works greatā¦ but I noticed the price on the web page just now. Something seems off. I bought mine from the same place in 2019 for 81euro + shipping. Now they list it as 161euro?!? Thatās frankly ridiculous.
Thatās similar to what I did when trying to solve my issues. Moved AI and headphones to different internal USB hubs, still had the same issue. With USB powered stuff itās apparently to do with coming from the same power source (i.e. the PC).
My things were both USB powered though. I think the tell on if itās a USB ground loop or dirty power unit would be if the POD Go buzzes when not hooked up via USB e.g. just direct to your amp.
@Kasper
Absolutely crazy price. My link showed as 155 euro before post and packaging. So I went for the analogue filter from Thomann, 30 euros and that includes patch cables.
Yes I think that is it for sure. No issue from the POD when the USB is disconnected, either via the AI or using its amp out into the Mustang. So regardless of the PSU being only 2 pins I donāt think that is the issue. I tried connecting the POD to my other AI (UMC1820) and got the same result. So as thatās just a case of swapping cables (I leave the AIs cabled up) it will be interesting to see if that is also resolved by the HD400 as well.
The Mustang III has a Ground selector for the Line Outs, which Iād pretty much set and forgotten about years back. So that explains why I do not hear the same issues when that is connected to either AI.
So in the mean time I am monitoring the POD via headphone, whilst doing some final tweaks via the editor and disconnecting the USB for rehearsals. The filter should arrive by the end of the week, so will let folks know if that has solved the issue.
Once again thanks for all the input.
Hmm, I hope it works for you! Not sure itās doing the same thing as the USB thing I liked. Where are you going to place that device in the chain? In any case, let us know! If it solves the problem then itāll be a good cheap optionā¦
If I disconnect the 1/4" TS cables from the PODās line outs but leave them connected to the AI the interference stops, even when the PODās USB is still connected to the PC. So the plan is to plug the patch cables into the line outs, then into the HD400 and the the TS into the box and onward to the AI. Like I say will let you know.
Update
The Behringer HD400 arrived today but sadly Thomann screwed up and I got a 10 pack of cable ties, rather than the patch cables, doh ! First time they have done that in a decade plus of orders and all sorted via chat.
Anyway as you may expect I have various assorted TS and TRS cables loitering around the āstudioā so I plumbed the HD into the POD with some 1Mtr shorties and hooked it all up to the Xenyx AI. And voila
No interference. Well a slight buzz loitering from the guitar but that stopped when muting the strings. So sorted.
BUT having the HD āfilterā in line has effected the output level and the POD signal arriving at the AI was down on volume. So for future work that will be factored in and accounted for. But as I have everything set up for tomorrowās Open Mic, it will be easier to run without the filter and with the USB disconnected. Its too late in the day to revisit levels and balance at this stage. However, no more nasty buzzing so job done.
Great to hear that sorted it Toby
