I have presumed that 3A
Actually, the current rating isn't going to matter. The transformer will fold back before the regulator does anyway. It's nice to have the current limit to handle short circuits and other faults. None of this matters for normal operation. Only for fault conditions. And even then, the current rating on the regulator isn't that important. Both will work. I merely specified the better of the two.
So go ahead and stick in any 7815 TO-220 type regulator you can find. It will work.
4 black RCA
Ok, I know this seems wierd. You need 2 red and 2 black for inputs and outputs. Then, I recommend buying 2 more (either color), because the ground solder ring is "borrowed" from the jack and used for the MONO switch and GND lug. It was the poor man's way to get the right sized ring.
Q120-ND the power cord
You can use any power cord. I selected this one because it has an extra level of braid/foil shielding surrounding the conductors. This helps to prevent hum pickup from the cord.
jh
