A lot of good suggestions as to partnering gear above. I will say this, the Croft/Harbeth is a fine combination, have listened to the P3's with Croft off and on and like the combination, very much to like there.
I currently use the Croft Micro 25 pre and Series 7 amp with Larsen 4 and Shahinian Larc speakers, certainly a different take than the Harbeth, but each have their own strengths.
As to cartridge, have read/heard Croft owners enjoying the Nagaoka's with their systems. I have an MP110 waiting for a turntable purchase at some point, will see how that part goes at some point.
In the meantime, enjoy your demo, trust your ears!