Can I run a preamp through a guitar amp?

I’m a musician and I have some experimental ideas for recording new sounds. Basically what I want to do is run a sound from a presonus pre amp (from a speaker/headphone port) through the input of a guitar amp. Then re-record it back into the DAW. My guitar amp has a really warm, fuzzy, organic sound that I can’t recreate digitally, so this is my idea to get said effect on instruments other than guitar. Sorta like this:
(Pre amp output) ------> (Amp Input) ------> (Amp output) ------> (Pre amp input)
I plan to have the preamp input channel muted to avoid any feedback.

My concern is that a guitar amp may fry my pre amp. Would it harm my pre amp if electricity was the wrong way into a speaker output? I don’t totally understand how guitar amps work and I’d rather not replace a $100 piece of hardware, so any input is welcome.