20A vs 15A Power Conditioners and can I even use a 20A one?

Hello all,

I am interested in adding a dedicated power conditioner for my power amplifier + subwoofer alone and have setled on either the Furman IT Reference 15i (15a) or the 20i (20a)

First of all, I know the outlet I use is a 15a outlet, but it does run back to a 20a breaker. I could swap this out to a proper 20a outlet, but I have heard if you are installing a 20a outlet, there should be no other devices running on this circuit and it should be dedicated. (This won't be the case) Also that there is a chance the wiring which runs to the 15a outlets (even though they go back to a 20a breaker) could be not equipped to handle 20a and could be a safety issue. Can anyone elaborate on this?

Will there be any sound quality difference, especially in regards to dynamics with the 20a vs the 15i version? I have seen many power conditioners with poor handling of dynamics. I will be running a 200WPC amplifer and a 370W powered subwoofer on the conditioner.
Post removed 

What other power conditioners would you reccomend I take a look at again? Again, I need something just for the amp/sub. The other gear is running off of a PS Audio Power Plant Premier, which while good, I find significantly reduces the dynamics of the power amplifier.

Synergistic Research Powercell 8UEF SE, 10UEF/FEQ, or 12UEF
Audioquest Niagara 5000
Core Power Technologies Equi=Core 1800
Shunyata Denali D2000T
Torus Power