OK i think i just found the answer which is YES. Below is from their online manual, which suggests one of the ways to ONLY use the additional amplifier to play music, is to unplug the speaker wire of the remaining speakers. I wasnt sure if running a separate amp would be like running a zone 2, where you would either switch between the speakers between zone 1 and zone 2, which would suck
Connecting additional amplifiers
This receiver has more than enough power for any home use, but it’s possible to add additional amplifiers to the subwoofer channel of your system using the pre-outs. With the VSX-1128, an amplifier can also be added to the front channel. To add amplifiers, connect as described below.
If you’re not using a subwoofer, change the front speaker setting (see Speaker Setting) to LARGE.
If you have two subwoofers, the second subwoofer can be connected to the SUBWOOFER 2 terminal. Connecting two subwoofers increases the bass sound to achieve more powerful sound reproduction. In this case, the same sound is output from the two subwoofers.
To hear sound only from the pre-outs, switch the speaker terminals to SP: OFF () or simply disconnect any speakers that are connected directly to the receiver.