Bi-amping with 2 2ch amps

I have one Pass X-150 and want to bi-amp.What is the best way to go about this staying with 2 X-150's. My pre is a Pass X2.5, speakers are vandy 3a sigs w/2 2Wq's. Thanks for any imput !
Vertical biamping. Hook up the highs of one speaker to one pair of amp outputs and then hook up the lows for the same speaker to the other pair of outputs on the same amp. So you have each amp powering one full speaker. Should sound great!

This article has info on vertical and active bi-amping: (
Thanks to both of you!! Vertical biamping is exactly what I was wondering about. I have Vandersteen X overs for the subs are they best near the pre or the amps, the run is 10'. Also would it be best to split at pre or amp , if cost wasn't a factor?
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The imput impedence of the X150 is 22 kohm balanced x2=44kohm I have the M5-HP set at 50 htz now. I would guess that it will be calculated at 88 htz so I would try 75 htz and 100 htz. What I meant to be asking was should I come out of the pre into the Xover and split the run right behind the xover or run a single cable into the xover near the amp then split right in front of the amp. If double biwireing gives a cleaner signal in speaker cable wouldn't it be true if I ran 2 interconnects from a split close to the pre, wouldn't that help the quality of signal? I'll have to check with some one to see if in fact I should use 88htz, you bring up a good question thanks.
Bob what are your thoughts on all this?
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Bob, Vandersteen recommends taking the imput impedence ( 22 kohm) and doubling when running balanced = 44 kohm. When I split the cable coming from the xover to both channels is the xover seeing 44 kohm & 44kohm which would be the total 88 kohm for the amp, or are you saying the total will stay 44 kohm so each channel becomes 11 kohm x2(11 in 11 out balanced) =22 kohm x2( boyh channels) = 44kohm? The M5-HP can be set at 20k, 33k, 50k, 75k, 100k, 150k, 200k, 300k and 400k.
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Bob wouldn't I double this = 22K ohm and use the 20K ohm setting ?
try horizontal too. The amp might prefer more similar loads in each channel.