ISOLO Choice-Guitar Version, Wireless Microphone System-EQ,Effect All in one Package

I have been waiting for this product for literally 15 years—ever since I got a vintage Martin D-41 that I did not want to modify (cut holes in) for a pickup system. The Skysonic FS-1 in sound-hole pickup combining a magnetic pickup and a mic was not bad, but nowhere near the quality of the iSolo Choice. Finally, this product does justice to a good acoustic like the Martin D-45 I am currently using it in. When I record that guitar, I typically record two channels simultaneously—the iSolo on one and a good recording mic on the other. The results are terrific.On stage, the system is also wonderful. I have used it on the D-45 (which has no other pick-up in it) and it performs great—no feedback.I also have tried it in my main stage guitar, a Martin HD-28 that has a Baggs Element pick-up hardwired in it. The iSolo Choice system paired with the Baggs system is really the ultimate acoustic guitar reinforcement system I have been looking for for years. Moreover, both systems are wireless as I use an ammoon Wireless Guitar Transmitter/Receiver system for the Baggs and plug the receiver end into the iSolo pedal/preamp. (BTW, I have two of these ammoon systems which I have reviewed separately. They are hands down the best wireless system of the four that I have tried.)The sole drawback I have found with the iSolo Choice is a major problem for pro musicians/performers. When I rack it with other pedals, I get a high-pitched hum that makes the iSolo unusable in that configuration. The pedal unit must not be shielded well (or something). When I use it standalone (with no other pedals), I do not get any noise or electro-magnetic interference.Note, this is not 60-cycle hum as I do not use wall power to power my pedal board. Rather, I use stand-alone 9-volt battery packs. I have used these for years on a number of different pedals and different pedal configurations and have never had any kind of hum problems. But, when I put the iSolo into the pedal board chain, I get this high-pitched hum. If I separately power the iSolo pedal and move it a couple feet from the rest of the pedals, the hum lessens but it’s still there.