15amp / 20amp PC's and Conditioners?

A 15A connection is physically different from a 20A connection. A 15A PC has a totally different connection than a 20A cord. Your equipment only has 15A connections, so you can't use a 20A cord with them. This in no way limits the quality. It's not a rating as much as it is a type.

Furman. Been in studio for years. Every well respected with sound designs without the BS from audiophile companies and their marketing crap. 

You can go higher on the rated output of the power
conditioner but not lower than the rated output of
your amp. In fact, I'd recommend the higher rated
power conditioner just to be safe.