Waiting on wire so not much progress on audio. Decided to put a volt meter where my factory clock was to watch voltage during runs. I pulled apart one of those volt meters that mount on top of batteries for the led readout.
Factory clock housing
Tore apart the housing. I had to glue in the 3 gray parts they are to adjust the factory clock and wouldn't look right with holes
Old clock
Led volt meter. The black wire is ground simple enough. If you look close you will see 2 holes at the top left and right. A piece of wire needs to be soldered to each, one is for the led and the other for the actual voltage read.
Soldered the connections to the factory pins inside the housing so I could use the factory plug. I used the constant power from battery and ground pin since the gauge shuts off after a minute or 2 of no voltage change. The other 2 pins are illumination and accessory and I just bent them out of the way since they are not used.
Finished product. The meter has a set screw on the back to adjust readout so I set with my dmm and now can keep up with my voltage on the fly.