Question regarding adding a poweramp to an integrated amp

Greetings, 

If I added a powered amplifier to an integrated amplifier via preouts, would the internal amplifier on the integrated turn off? Or will it still run and generate heat regardless?

I have a Lexicon RV-5 and love it and it’s functioning fine, but I am concerned at the age and the fact that nobody wants to touch it in regards to servicing it.  I wanted to get it recapped and even pyramid audio won’t due it. Basically I’d feel more comfortable buying a poweramp if I knew I’d be preserving the internal amplifier.