Ok... I have recently purchased a set of psb synchrony ones and a NAD M3 amp(180 wpc)... if were to add another amp, say a Rotel RB-1170(130 wpc) for bi-amping... which way would make the most sense to wire them up? NAD for the Highs and Rotel for the Lows? or vice versa???
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looks like what you are wanting to try out is "dual amping" your speakers 'cuz you will continue to use the factory provided built-in x-overs.
This might or might not be beneficial, as others have already stated.
The highest probability of success (if there is any for your situation) will occur when you have 2 identical stereo amps OR 4 identical mono amps 'cuz you will not have to worry about amplifier gain, amplifier sensitivity, amplifier sonics, amplifier headroom, amplifier current delivery capability, etc. For any other situation, it's a hit or miss - the difference in the different amplifiers' capability might negate any benefit of dual-amping.
True biamping is more complex that simply dual-amping - the ultra-purist (& IMO the bold) will completely gutt or simply disconnect the entire factory provided x-over & use an external (tube/s.s) xover & the purist will disconnect the bass xover while keeping the mid/tweeter xover & still use an external xover. Usually the external xover is used between the preamp & power amp to avoid using multiple preamps.