This is a tricky one - the Alpha P9 is an excellent power amp with lots of control and power. Certainly Arcam integrateds don't have the pure current of other brands, hence they thrive when bi-amped. The only thing I can suggest is either P85 or one of the FMJ power amps such as the P25. In all truth, the latter maybe an overkill.
You may have to look at more drastic changes: I know from personal experience, the budget end of the DIVA range, although very good, need a speaker that's easy to drive. Perhaps a minimum of 90db, but I know absolutely nowt about Heybrook speakers. If the power amp suggestion doesn't work then look at a different amp. When I auditioned the A70 and compared it to my A65+ it sounded timid.
I would keep the options open and maybe look at the Roksan Kandy LIII, which is a powerhouse - it is also blessed, like Arcams, with a fabulous phono stage and has pretty much as many inputs too. IMHO it's a different animal to the K2 and A70.