Testimony IS evidence.
However, even to violate you, they would have to show the court that you violated the terms of your probation. Don't give them a reason to violate it. And don't engage in activity that could be misconstrued as criminal or otherwise in violation of your probation.
Besides, recording your conversation with your PO won't prevent others from lying about you. So, if other people are lying about you and getting you violated through hearsay, recording your conversation with your PO won't do you any good, anyway. Is there some OTHER reason you want to record your PO?

