It's conceivable that the JB3 could induce some noise into the analog circuits of the UA-5 simply by being close enough. The pre is doing major gain and anything that gets in there is amplified. Try a recording, monitoring thru headphones on the JB3. Don't hook up any mics, crank the UA-5 gain and move the JB3 around different spots of the UA-5 and see if you can get some noise coming thru the headphones.
Make sure to actually record on the JB3 so you get all the hard drive activity of normal operation. The hard drive activity is every 9 seconds so stay at least that long in each position.
fwiw I tried this yesterday with mics hooked up and the UA-5 gain all the way up and couldn't get ANY noise induced from moving the JB3 all around the case and cables. So if it is there, it's well below the noise floor.
Topic: UA-5 getting interference from JB3? (Read 4951 times)