I need a power supply for my M-Audio Keystation 61es MIDI keyboard, and I think I might have one that will work for it. The user manual for the keyboard says this: But then their website is selling a 9v 500mA as the proper replacement: http://www.m-audio.com/products/en_us/PowerSupply9VDC500mA.html [Broken] And every other online retailer sells a 500mA supply as the replacement: http://accessories.musiciansfriend....upply?sku=500930&CJAID=10381297&CJPID=2179950 A little bit confusing, but I have two laying around that might work, one is 9V 800mA and the other is 9V 300mA. Do you think either of these will be safe? If so, which one? Also, do the "input" specs on the supply matter much?