need to test a used amp on the wrong sub

Hello, just snagged a gently used JL 500/1 amp that I'm planning to use to upgrade my bass in my car with. Unfortunately I don't have have that new sub, and I have 7 days to return this amp if it isn't working properly. What I'd like to do is wire the amp to my current sub woofer for 5 minutes to make sure its fully working, but I'm afraid to blow this sub. My current sub is a 10" Polk/Momo MM2104    - reccomended 300W RMS    - maximum 600W peak Will running this sub on the 500W RMS/~1000W Peak JL 500/1 amp blow the speaker if I'm at very low gain levels and volume for less than 5 minutes? Is there a better way to test Amp functionality without a sub? Thanks, great forum, so glad to have stumbled onto it!

As long as you don't turn it up too loud, you should be fine.  All you are testing for is whether it turns on and makes sound anyway.  I have tested many amplifiers, huge monoblocks included, with a small 6" midrange we have on top of our bench tester.