Good choice. You'll be able to get far more than 85db in that room with the 3700. You should just play your music at the level you like. If you don't get distortion and it doesn't shut off, you're good. It's extremely unlikely you'll need to use an extra amp to lighten the load on the receiver.
If you listen to loud music often, for longevity you should get the fan that was mentioned
If you listen to loud music often, for longevity you should get the fan that was mentioned