Hey,
The Panasonic isn't really worth buying a power source for, if you have an extra receiver lying around that you can use to power it, that would be fine....or if you can buy a $20 used receiver, that would work too. But that's about the best you should do for it.
You should be able to use the JVC with your AVR. Since it's powered, I assume it has a RCA in jack that you would plug into the sub-out. If it takes a wire connection, you'd just cut off one end of the RCA wire...or you can buy a cable that only has the RCA plug on one end.
If you are willing, perhaps the best route is to get a new sub, even a cheap one should be quite a bit more capable than those two. On the bottom end there's something like the BIC F12 or Dayton Audio SUB-1200. The BIC usually hovers around $180 but will go on sale here and there, the Dayton is usually around $130. Probably the next step up would be the NXG NX-BAS-500 or Mordaunt Short Aviano 7 which are $270 and $290.