When you do come to the stage of letting them talk, make sure to brief your champion on expected questions and provide all the information they need to answer those questions.
But this is a very powerful card you have and you want to think through how / when to use it. Two suggestions I've seen work well:
tell the investor - out of respect for our client's time, we'll schedule a reference call when we see a fit; make the investor earn that call
have the client record a Loom with the most common questions and use that earlier in the conversation