Stupid sub woofer connection question

[Mochamoon]

Pardon my ignorance please. My set up is Audiophonics hpa-s400et, Topping D90se, Topping Pre90. So my question is can I run a powered Sub off the RCA output connection on the Pre90?
I've already got 4 speakers hooked to the 2 channel Amp. It sounds really good to my non-golden ears. Just thinking a sub may round out the experience.
Thanks in advance.

 

[DonH56]

Yes, though you may want to pick up a crossover (analog or digital) to offload the main speakers and make it easier to integrate the sub.

 

[Mochamoon]

Thank you