The XR50 doesn't need to be heavy as it amplifies digitally and uses different circuitry than a conventional audio amp. You could make it heavy by putting lead in the case if you wish.

I guess it could be lead from the US if it made one feel better...
BTW I have a Panasonic DMC-LC33 digital camera, Panasonic duplexing laser printer, S55 CD player. Everything works well. Anything I (or my parents) ever bought made by Panasonic (or National as it was known way back when) has always been a good value and lasted forever.
Running analog signals into the XR50 is no problem. Sounds just fine.