There have been many threads here on this topic, several members who have tried upgraded power cords have noticed an improvement. Your issue is at what level of gear, the only way to know for sure is to try one. I'd say if the unit has a detachable cord it could benefit. I say that because generally only better quality gear will have that feature. Several members seemed to have good luck with the Pangea cords.

My Bryston owner's manual actually says not to use any other cable than the one provided. They really don't say why. When I tried an aftermarket power cable for myself, not on the Bryston, I noticed such an improvement I went out the next day and bought enough to replace all of mine. The most noticeable improvement was on my CD player and phono stage. The improvement I heard was very real, at the time the cable was given to me to try I was convinced nothing would happen but the result is what changed my mind.