The main problem is that your ability to "place" a sound along the L-R axis gets messed up, impacting what is variously called "imaging", "soundstage" etc...

Having two identical speakers side-by-side doesn't seem to be a bit issue but having the tweeter and woofer in a different vertical axis does seem to be a problem since different frequencies come out at different horizontal positions. This isn't a problem when the speakers are oriented vertically because we don't have "top and bottom channels", ie we don't try to image vertically. This is why pretty much all speakers have the drivers oriented in a vertical column.

Center channels play a bit of a trick to get around this. The "D'Appolito" arrangement (two woofers with a tweeter in the middle) works pretty well because the two woofers act pretty much like a single woofer in between the two, ie located on top of the tweeter. The VP150's TWWWT arrangement works the same way -- the outside pair of tweeters, the middle pair of woofers and the center woofer all sound to your ear as if the sound is coming from a single point.

Again, where this *doesn't* work is if you just have tweeter and woofer side by side because you end up with low notes over to one side, high notes over to the other side, and during the crossover region (at least an octave) you have a slightly different location for each frequency.

You can hear this pretty easily -- stand your current speakers vertically and listen to the "imaging", then lay them on their sides and listen to the same track again. Unless your room is really live (which messes up the imaging anyways) you should find the imaging much less sharp the second time.


M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8