OK, I tried some more tests. I can confirm that when I turn on the battery pack, I am hearing the interference noise.
Without the battery, I can adjust the gain on the Tinybox (low, med, high) with no issues, and adjust the gain on the Tascam dr-2d with no issues. I can plug the battery pack into the tascam with no issue, but as soon as I hit the power/on button on the battery pack the interference starts. I tried different cables from the battery to the recorder, and the interference remains. I coiled the CA cables, and even tried my pair of CA14 omnis, interference still there. I moved the battery, tinybox and recorder close together and farther apart, all still had the interference. It only goes away when the battery is turned off.
I am only feeding the Tascam recorder with the battery pack, nothing else.
The battery is a lithium ion 5v output, 6000mah battery pack. The cable is a USB on the battery pack end to a B tip on the recorder end. I charge the battery pack with a regular mini-usb DC charger. It is not switchable to different outputs, and it is not just a bank of cells. I assume inside is a single li-ion cell, which is all wrapped in a plastic enclosure.
I used this exact setup, and also with phantom powered Busman bsc1s instead of the small CAs, and it worked fine at least 10 shows worth.
The first show this noise appeared was at Tweedy.
Is this just a crappy battery which is no good after a few uses? It seems to still hold a charge fine and power the device, the only difference is that this noise has been introduced. I am not too clear on if this is something that happens with external batteries, or if I need a better quality battery to prevent it happening again.
As I stated, I am a huge fan of the extended life (up to 12 hours), instead of the palty 3 hours I get from regular batteries.
Any more ideas?