I'm sorry buddy but I'm having a little trouble understanding your question so I will do my best explain what I think you want to know.
The lower the hz number the more bassy it is (thats the scientific definition)
If you set the crossover for the speakers in the receiver to 60hz you are telling the receiver to send the frequencies from 60hz & UP to the speaker (60hz-20khz) The frequencies below 60hz for the speakers will be redirected to the sub. This way the speakers are safe from frequencies that can damage them.
The sub is designed to handle low bass. So don't worry about giving it too much bass. As long as the volume setting on the sub is correct compared to the speakers then you are good. By giving it frequencies that normally go to the speaker, using the crossover in the receiver, your totally fine!
A typical sub can easily play up to 120+hz so it can be crossed over that high no prob.
On average (this is in no means set in stone, just a guideline) speakers that have these specs should be crossed over at about this point. Examples below:
Speaker 1. -3dB at 30hz, crossover at 45hz-80hz
Speaker 2. -3dB at 40hz, crossover at 60hz-90hz
Speaker 3. -3dB at 50hz, crossover at 75hz-100hz
Like I said, if you have the sub's volume set correctly then you don't have to worry about overdriving or damaging it. If you hear distortion or some sort of popping noise then turn the master volume or sub volume down a bit. Use common sense!
Hope this helps!!