[quote name='sockdeluxe_mikey' post='1172442' date='Mar 22 2011, 06:57 PM']A very good question, this one!
The Boss ACA input is basically going to be a pedal that runs on 9V, EXCEPT there is a resister crossed over the power that basically means that it needs 12V to run at 9V - I have absolutely no idea why this! So, the Boss adaptor may say 9V input and the pedal may say it needs 9V, but actually it needs 12V.
Therefore, all you need to do is run 12V into the pedal. This can obviously be done by either a separate dedicated (centre negative?) adaptor, or (like I and others do) get a dedicated power brick and use the 12V (centre negative?) tap from that.
A Boss ACA pedal will only run at 9V if a) it's running on batteries, or intaking 12V from the outside. If you input 9V, it'll run a few volts below that and the OC-2 actually sounds a bit pants like this. You can also tell this is happening because the 'on' LED is noticeably darker when not running at 9V internally.
Hope this helps![/quote]
Interesting!
I have a T Rex psu so I'll look into the 12v aspect.