[AMM-1 watts or realtime power not working]

Tried both. I did music also so that I would at least have transients powerful enough so that I could achieve peaks that I knew for a fact, beyond any stretch of the imagination were more than an order of magnitude greater than .9 to 2 watts. 

[AMM-1 watts or realtime power not working]

I think one time I got it to show 2 watts, but mostly it says 0 watts.

One speaker lead is running through the hole in the meter, and the leads are connected(actually screwed into) to the speaker terminals. 

 

https://www.mediafire.com/file/g5le0ybki1lohnb/out.mp4/file

[Wire 6yr old XP3000 with brand new XP3000's? Is this bad idea?]

I don't know if it's relevant for these AGM types of batteries, but you can take lead acid batteries to many auto supply stores and they have a gadget to test them under realistic load. Even walmart can do this.

Once, I thought my battery was going out and I happened to be within walking distance of a walmart. I was going to just buy a new battery on the spot, but they tested the old battery and said it was good. They printed a little slip of paper with some specs and tests the battery was capable of passing. I would bet autozone or similar could do the same. Worth calling one of them to find out.