Your Monitor Audio speakers are a fairly benign load on paper (90db @4 ohms) and sound transparent and quite resolving, so you don’t need a massively powerful amp, but the PL300’s need some tube-like liquidity & musicality. So i’m going to throw a curve ball at you and suggest you would get a bigger gain by selling your current amps & upgrading to a high end integrated amp such as a Pass Labs INT-250 or a 2nd hand Vitus SIA-025. Though good 2nd hand examples of the Vitus are rare on the used market.
The upshot is with one less component, you could use the savings to invest elsewhere in your system such as better cables or isolation.
The upshot is with one less component, you could use the savings to invest elsewhere in your system such as better cables or isolation.