New power cord needed for speaker with powered subwoofer?

Amg56,

 I have an Isotek Orion power conditioner with Isotek power cord.

There is no benefit in substituting an "audiophile approved" power cord to your sub.

I use two PS Audio P10 regenerators for my system, and this past year I upgraded my system's sound purely with changes in aftermarket power cords.  Yep, even with a really good regenerator between the wall and the equipment I found the improvement significant enough to plunk down my dollars, and this was with a significant home trial period allowed.  Just the change in power cords seem to bring my system's sound significantly closer to the sound of live music, with better dynamics and truer tonal quality.  Just my experience, in my system, to my tastes, YMMV, etc.

I'm an engineer, and I used to believe on principle that power cords could not make a difference (assuming adequate current capability).  But actual listening trials converted me from a skeptic on "theory" into a believer in practice.  I'm just saying "Give it a try".  With return privileges is best, then what do you have to lose?

There are many companies that will give you an audition period for their power cords and all you have to do is pay for return shipping.
Try it yourself and let your ears be the judge, as mentioned by jbrrp1.