I've been using a R55 guitar pedal before, but now I've lost the adapter. Beneath the input thingy it says 9VDC, 300mA and theres a +, a little dot, and a - inside three different circles. Can I use any kind of adapter for this, or do I have to use one that says exactly 9VDC, 300mA or I'll blow up and die? I am very inexperienced with these kinda things..