Thanks, this was my thinking - no harm in trying it i guess. The pedal it's powering takes two 9v batteries but via the power input it indicates 25v max DC, and I trie dit at 12v yesterday which sounded the same as usual - though I did notice a slight popping when engaging or disengaging the pedal which you don't get with batteries - I wondered if it's because I'm supplying it with an odd voltage (hence wanting to try 18v)