The unit worked first time. No hum and the volume level seems about right.
I am using a Denon DL-301 II which outputs 0.4mV
Trimmers, set the Impedance to 100ohm and gain to 900ohm, seems fine at that, level is just a little lower than my CD player. I may adjust when I have the hood off to fit the longer battery bolt.
The 13.6 voltage after charging dropped off and it settled down after about 8hrs to 12.4v where it remained for several hours playing. Again nice to see identical readings for both batteries.
First impressions - Very nice, quite, with lots of detail and strong tight bass, slightly wooly mid range, but it's early days yet, will give it some run time, but already very impressive.