My fully differential AVC-1 uses a 2.1 mm x 5.5 mm DC barrel connector and yes, the power is used only to run the control circuits. I'd be surprised if the TAP-X used a different DC barrel connector, but it's possible.
My AVC-1 was set up to use 12V power in order to support integrated 12V triggers that I use to turn on my amps, so I don't have the specs for the standard 9V power supply, though I suspect that 1A is more than enough. (I'm not even sure where my 12V power supply is, as I'm running off of a battery... though I should probably find it just to make sure it doesn't wander off!)