Since the 1050 has two pair of speaker terminals it would be very simple to run a second pair of speaker cables to the high-level inputs of the sub. They don't need to be as large as your main speaker cables since they're carrying just the frequency and amplitude information and very little current.
I found it easier to integrate an HSU sub using the high-level inputs rather than the low-level and that is the method HSU recommends.
I found it easier to integrate an HSU sub using the high-level inputs rather than the low-level and that is the method HSU recommends.