Thanks. Appreciate it Josh, the actual adapter is 500mv.....it says in the manual that it needs 300mv minimum. Right now I'm just using the adapter in the back of the rack to power it.
I assume you mean mA (milliamp) and not mV (millivolt). I can assure you that the actual current is no where near 300mA. It looks surprisingly similar to a 2x8 MIDI thru box design I did in the '80s. Mine also had 3 position slide switches, but the 3rd position was off. Same LEDs blinking with activity. I sold quite a few of them at the time, so perhaps it was an inspiration!
I can't make out the polarity in your picture, but assuming the standard Boss size barrels don't fit and center positive, then the red Line6 cable will be correct. Boss are 2.1mm center pin and the red ones are 2.5mm. Now go plug it in and tell us that it works.
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