I'm thinking not a bot. but would love to hear from the OP to defend himself.
there is no reason to compromise. Buy a high quality 2 channel amp with more than one input. On input A run the low level input from your 2 channel preamp, this will be your 2 channel sound set up.
On input B run the low level output from the front speaker from your 5 channel receiver.
this allows you to upgrade your 2 channel system independent of your 5+ channel system. I have had 5 different 2 channel amps in my system in the past 2 years, all ready to play movies when called upon.
I currently have a 100 wpc Denon surround sound system. I run pre-out to my current amp which is a 2.3 wpc SET. 2 nights ago I watched Guardians of the Galaxy at theatre volume, shaking the house and the small amp was more than able to drive the front speakers.
Afterwards I switched back to Input A and played some smooth jazz.