Let me say first I know very little about home theater.
I have a JVC TH-M606 1000 watt DVD system that died. I think it's the boards in the subwoofer. While I don't think it is worth the money to have repaired, I, instead purchased a used Yamaha RX-V571 receiver.(Haven't received it yet) I would like to know if I can safely use the JVC speakers with the Yamaha receiver.
The speaker specs are 115W @ 4 ohm for the 2 surround and center speakers, 125W @ 4 ohm for the 2 front, and 125W @ 4 ohm 100hz for the powered subwoofer.(The sub woofer I would have to unhook the power to it). Let me say the actual ohm readings on the speakers are in the 7.5 range and the subwoofer reads about 5.4 ohms.
The receiver specs are 105 watt @ 8 ohm THD 0.9% 7 channels.
You should be able to safely use the Yamaha receiver with the JVC speakers, just not sure if the JVC subwoofer would also work? If the subwoofer amp is dead a RCA line-in connection won't work. If the subwoofer accepts regular speaker cables, then it could work using power from the receiver.
Two worst case scenarios could happen.
1) You play the system too loud, the JVC speaker drivers could blow as they are probably not capable of handling the greater (cleaner) power of the Yamaha receiver.
2) When the receiver uses 4 ohm power for a long period of time it can potentially overheat. Although the receiver would likely shutdown first to prevent that from happening.
In any case you should most likely be fine. Enjoy.