Please forgive my ignorance on this subject, I am in the learning phase......
In the PLX1602 manual (page 15), it does say that it accepts unbalanced inputs. Balanced is 12k ohms and unbalanced is 6k ohms, but I have no clue what that means:
I am more than likely going with the 1602, it is closer and a little cheaper than the GX-5 for me to purchase.
No worries. I would chose the 1602 as well. Higher quality components. I believe the 1602 has 2 capacitors per channel as opposed to the one per channel in the GX. The GX is a quality amp but QSC's entry level offering.
The PLX does accept an unbalanced signal. You would need an RCA to XLR or RCA to 1/4" TRS. An unbalanced signal is ~ 12db lower than balanced. Have a go and see how it works out. Worst case you can pick up a converter later if you feel it necessary.