Does anyone play two pairs of speakers at the same time?

my kef r-300 & elac  adante  61  complement each other fantastically

In the 1970's, I ran stacked Advents with a Phase Linear 400.  Later, I ran stacked B&W DM14's with this amp, and later with Audire electronics.  Eventually, I had some Acoustat electeostatic panels which I paired with the DM'14's.  All were good in their time period, but now I use B&W 803's, interestingly stacked on my 10" subs that I drove with a second Audire amp and preamp, until recently, when a botched repair, a shorting accident killed my electronics.  I am searching for an Audire Diffet 3 (maybe Diffet 2) and Audire Forte or better to pair with my Bryston amp and preamp.  Anyone?

On my vintage system I use JBL 166's and JBL 4312A's in tandem. What the 4312A lack (Highs) the 166's have in spades and likewise the Midrange of the 4312 make up for what the 166 is short on.  Its a match made in heaven for 70's Classic Rock. Havent found 1 speaker that has it all.

   you could be losing it. 
  For stacked quads work
 real nice  I've heard them   be careful  a lot of the same model speaker won't work at all
 well   use the MTM set up   good luck   don't waist much time on this 
 

I run several 2-channel systems and have multiple speakers in two of them that I listen to simultaneously (the speakers, not the systems). My favorite actually has three sets of speakers....ADS L-570s, an ancient pair of Genesis Physics 1s, and a pair of Totem mites. The amp is an Adcom GFA-555ii with a DH-110 preamp. The little Mites are the real secret in this mix, as they are somewhat laid-back/recessed to my ears, while the ADS and Genesis are really in your face comparatively. But the mixture works really well, no matter which two pair are being engaged at the time.
The other system is a B&K 125.2 amp/Cary Audio SL-100 combo, mated with Energy C-2s and a small pair of M&K K-5s that are floor-mounted at the base of the C-2 speaker stands. Both systems also employ powered subs.