Well I don’t think I am pretty certain you have no idea what size the capacitor needs to be. That capacitor in the Furman is fairly useless other than for higher frequency EMI which it will help. It’s voltage tracks AC voltage and is only above the reflected voltage of the power supply capacitors for a short period of time.
That capacitor is going to be at most about 200uF. That’s a physically large cap. Probably its more like 100uf. Peak AC voltage on 120V is 168. Let’s say we have a DC rail on a linear supply of 40v. At best, that 200uF is like 168^2 / 40^2 = 3500uF added to the amp DC rail. Most good amps have far more than that. Because the current transfer is only for short period where reflected AC on the cap is above DC the effective adder in uF is effectively maybe 1/2 that and practically much less.
But hey, why don’t you tell us how it works.
Now if your amp has a switching power supply, then yes this will help, not in power delivery but reduced EMI especially if that power supply already has active power factor correction.