I wouldn't go with a P25. I would definetly sort out something though, as the GS60's are not easy to drive at all and I don't think you're getting the full experience they can deliver. Either another set of P1's, or something more substantial. Musical Fidelity M6 power amp or similar.
A lot of people think that because speakers 'can' be biwired/biamped, that they must sound better that way
I fell into that trap and convinced myself that bi amping was better for my Monitor Audio silvers. Ive since changed everything over to single wired and to my ears sounds far better.
Biamping sounds 'different', but its usually down to 'phase shifts' (physically changing the way it should sound). So bass and treble become more pronounced, but to detriment to wherever the crossover point is on the speakers. Some speakers are designed to work biamped, but in my experience, most simply have the extra terminals simply because consumers demand they have them
Personally id recommend sticking with what you have, but use the same speaker cable as jumpers
I can only give comment on biamping in general because I am not familiar with both the ARCAM and MA speakers but I do kind of agree that not all the time bi amping will provide better sound, different maybe but not all the time better. In my experience, I started off with MF XA1 to drive TDL RTL3SE and soon after that Heybrook Optima. After a year, I purchased a pair of XA50s monoblocks. Snce then, I have always biamped my speakers ranging from TDL, Heybrook, Mission, EPOS and ProAc D18 for the past 11 years. Each time I change my speakers, I will compare between non biamped and biamp, and biamp always sounds better.
Many will argue that my set up is not truly biamp as XA1 is an integrated amp and not a pre amp but it is still running separately the tweeters and the XA50 running the bass drivers.
However, things are different after I upgraded to MF M6i integrated amp. Since my local dealer does not have the matching M6 PRX Power amp, he loaned me a A3 CR power amp to biamp my ProAc. Had it for a month before returning the power amp. Something didnt sound right biamping between an M6i at 200 WPC and an A3CR at 125 WPC. it might be the power different or gain or even just the topology between an A3 and M6 amps. Currently I am not biamping my ProAc D18 but trying to get my hands on an M6 PRX.
So my advice is to try it out for yourself. If you like the sound of biamping, then stick with it. If not, dont.