It looks like theMonitor Audio Gold 300 are significantly expensive speakers, and capable of pretty fine detail. The Emotiva amp is probably not in that category. I looked it up to find it's yet another amp that Emotiva has introduced with great fanfare to only retire after a shortish life.
I had an XPA-3 for my 2 channel system, and my greatest criticism of it was a bright/harsh sound at medium to higher volumes. I had 3 Emotiva components, and that was an issue for sure.
Your P5 probably mitigates this issue if it's present in the XPA-200, but such a low budget amp(how much did Emotiva pay to have it built with lower grade parts) will have limitations in sonics IMHO.
I've recently acquired the P5 myself and have been pretty impressed with it for the money. I guess the question is, what goals do you have for this upgrade? Because as far as money goes, you can spend some crazy amounts but without an end game in mind, you could be in for disappointment.
That said, most are after that last 3-5 percent of sonic bliss. What you need is an amp that will have a synergy with your speakers, and I don't really know which brands are a good fit for the Monitor Audio Golds. Perhaps some owners could chime it, Pass Labs is certainly one of the better options, as is Sim Audio.