Bi-amping speakers - Vertical or Horizontal

I'm trying to get more out of my ProAc 2.5s and am thinking about bi-amping as their x-over would allow this. I'm using a 300B amp from Air Tight and need advice as to what other amp I could use. I'd like to stick with SET but can see where push/pull would also work. I once tried this with 2A3 mono-blocks on the tweeter and a 25wt OTL on the woofers. Got too complicated (Cary amps with all those switches, I know...I'm lazy!). I'd like advice also as to whether I should try vertical bi-amping (two stereo amps, one on each speaker) and woder if anyone has tried this vs. one amp driving the tweeters of both speakers and one amp driving the woofers.