The original leads are 20 AWG, and clip onto a header as shown in the photo.
Beside that two pin header is a 15 amp rated Phoenix connecter that's a optional power supply connector.
I ran 16 AWG silver plated PTFE wire from the new binding posts to the Phoenix connecter.
These units were sold complete, as kits, and as individual boards. Many were custom configured, hence the dual power supply connections.
Last I looked, some of the boards were still available as well as empty chassis.
These supposedly have a onboard SMPS for the logic chips and such, so a very high quality power supply doesn't make much difference from what I've read.
I see it as a worthwhile upgrade anyway.
Works great. Listening to George Strait on Austin City Limits.