Dedicated line questions...

Did a search, but can’t come up with a good answer. I am considering the install of a dedicated line. The general consensus is a 20amp circuit. How does this rectify with a full system designed around 15amp components/cords. I already have PS audio receptacles, and have upgraded/cleaned up all the other outlets on the current circuit, but it is still noisy. Would installing a 20amp circuit require a refit of gear or just 15-20 amp power cords? I don’t run big mono’s and really only need one line. Would a dedicated 15 suffice?  Yeah, fairly clueless in this realm.