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

Great! In the past I have only done large Advents stacked and some smaller stand mounts, also tweeter to tweeter. Now I'm playing my highly modified Klipsch Quartets and RF 3 lll together and enjoying the sound.

Bilaltata,  you will see on the first page of this thread the success I had (and still have) running Focal Utopias and Focal Electra 1038BE2’s together.  What I’ve  done since then to make them even better in performing as a pair is muting the tweeters on the Electra 1038 BE’s.  Two pairs of tweeters can compete with each other and creat comb filtering.  If you mute one pair, you may find the imaging and overall sound is even better, beating what you have already achieved.   

I have found that certain combinations of speaker pairs produce a better sound than the single pair alone



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Yes I've been experiementing lately and found this to be 100% true.
1 speaker will not make magic happen.
My previous local tech had stacked Acoustic Reserach from the 1970's, sounded great
Richard Gray stacks the Realistic Rat Shak Nova 7B's. Sound great. 
I am stacking a  high sens 91db  FR with dual low sens 87 db Seas W18 midwoofer, xover at 2k, about to adda  2.2 cap and bring this down to 1600hz. 
The 5 inch FR whizzzer cone lacks the low end, the dual W18's come in beautifully.
Success at pairing low sens + relatively high sens.
Pairing dif speakers together is really the only way to go.
This is the new high fidelity. 

Not this week maybe never.

, at least the efficiency should be in similar range.


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Im running 91 sens FR with SEAS W18E001 dual each channel and having success, But best to cross the W18  low, say 1500hz. This adds a  bass floor to the 4,5 or 6.5 inch FR. 
Now the FR at 97db, the W18's at 87db won;t work. 
So agree, sens has to be at least close

I'm about to go SET amp  and dump the Defy7,,so I might have to dump the W18's and find a  higher sens bass unit to go with the Voxativ 8 AC1A