Radical thought- Use 2 pair of speakers

Ok this sounds crazy at first but, is it possible and practical to hook up two sets of speakers for your mains. Each pair has it's own unique characteristics to why not add them together? It is still a 2 channel system. A bigger sound stage? If you have two matched amps, dedicate one to each? I know there are many reason why this cuts accross conventional logic but has anyone tested this theory?
the idea isn't radical, has been done with stacked advents, and dahlquists, probably others. I suspect the results you get from mixing 2 diff speakers will be un-predictable at best. But if it works when trying it, and doesn't create impedance issues, more power to ya.
Each pair has (its) own unique characteristics to why not add them together
Because most likely you'll have more of cancellation and addition than complementarity, resulting in nulls & humps.
But... you never know!
Seems like it would be hard to get them to image well with such a large baffle area. (I guess I assumed you meant they would sit side by side?)
You are forgetting that benefits are not always additive. Sub woofers have long wavelengths, which are not directional to our ears, and hence can be additive. Mid range and tweeter frequencies are not additive....the result will be excessive comb filtering or a vague atmospheric sound that totally lacks focus. Even on a surround system the speakers should all match in timbre and characteristics (means you should really use the same speakers to get the most benefit).

Surround sound only works because the speakers are separated distinctly and the channel information fed to each speaker is specific for that arrangement, including delay adjustments according to specific speaker/listener positions.
Many recoriding studios use two different sets of monitors at once. If it works it works...

I have done this multiple times over the years having been inspired by my friend's older brother's system(this is back in the 70's) that had matching Royal speakers stacked vertically. I remember he had a Scott tube amp and a AR turntable in separate room and this system rocked. I have had mostly negative results combining unmatched pairs.
When building multi-channel systems, it's recommended to have timbre matched speakers all around. The same speaker in each channel is considered ideal to create a "wall of sound". I now apply this approach and I'm currently using two pairs of Realistic Mimimus 7's stacked vertically and wired in series in my kitchen's two channel set up. With the extra pair, I have better bass. I have large speaker sound with a small speaker footprint.
The old, OLD, "Sweet 16" speaker project from Popular Electronics used 16 cheap 5" speakers on each side (but just one box per side), the theory being that crummy speakers driven very little together might produce good sound. My personal opinion is that Bose stole this idea and made a mint. I agree with the posts that say try different speakers, not two pair of the same. Let them 'average out' the sound. Plus the greater power capacity you get with more speakers. Don't spend big bucks, experiment first. I think what will suffer, from what I've heard using multiple speakers, is imaging. Good luck!
Tarsando...Professor Bose had a 24-driver (mono) system in the MIT music library in 1961. I don't know when the "sweet 16" project was published.

The Megaline speakers which Albertporter praises are described as a "line array". (Line arrays can sound great). However, the Megalines actually consist of three enclosures which are stacked.
Hmmm. sounds like this could be fun to try. I will have to wait until my larger towers are repaired...waiting for tweeters. I will let you know what happens but the plan is to place them in the same plane.
A while ago, just for the fun of it, I did a "stacked" Eminent Technology LFT-8A speaker system. Had eight channels totalling 2,400 watts into 4 ohms pumping into them biwired. I tell you, it was one of the most wickely huge sounds I've ever heard from a system. There are many times I wish I still had it set up because it made me FEEL I was at a concert. It literally made "wall to wall" sound stage. I had two Vandersteen subs going as well. A system built for pure fun and I sure did have it! Enjoy playing around with it! This hobby is supposed to be fun!
Just throwing different brand speakers together may result in something similar to what the college cafeteria does with leftovers... could get messy.
Eldartford--interesting. My memory is not pinpoint by any means but I wouldn't be surprised if the Sweet 16 article dated from the very late '50's. I could research it but won't--could be that I am just plain wrong. Thanks for the info.
Tarsando...It was 1956 when I heard the Bose system at MIT...not 1961. (I mixed up dates of high school graduation and college!) If you google "sweet sixteen speaker" you will find that it was Jan 1961. You will also see a lot of interesting info on multidriver systems.
I guess I am beyond Radical, because I use 2 completely separated and dedicated audio systems for my own 2 channel surround sound.
Why not have one kickin setup in front, and in the rear, another kickin system.
The trick is to get the same sound,
patience and much listening period.
I use a single Stereo 500wpc.@4ohms amplifier in front,a lovely Velodyne F15ooR for the ground work.Mains are Klipsch ChorusII's with JBL L19 on top,then JBL L100 on very top,JBL are sideway's.
Rear another Stereo 500wpc.@4ohms amplifier and another Velodyne 15"sub. to keep the foundation seamless.2 15" horn loaded speakers on top of 2 12" 3 way speakers.
I simply send a loop from my Museateax Melior Pre-Amp to my Musical Fidelity pre-amp. Listening the whole room in Redbook,SACD or DVD Audio mode must be heard... if you like exactly what is on the Disc like I do,The Sony XA7ES plus Benchmark's Dac1 with Audio Alchemy's Data link(no signal loss)Transparent Audio's Super Power cord brings it like so many others can't.
It truly is like a metamorphosis occurs where by the notes seem to hang in the air as if suspended...
101db.Sensitive speakers with clean power and pure source,have that "Jump Factor" that very few speakers share.
Where every detail is reproduced clearly,like breathing, clapping ,drink glasses clanging together, cash register's, all backround sound's heard clearly.
The very inflection of the guitar or bass is represented as is the long decay, or delay...
If one system fills half the room(Robert Harley's Guide To High-End page 372 fig.A-5)
Then why not put another
sytem on the other side of the room?
I did, and after attending many Live events in Jazz Clubs or Out doors I have been very fortunate to see and hear some of the Greats.And now, I enjoy
that same Dynamic slam and clarity,the very essence of the MUSIC! Pro's use Line Array's to fill large area's;I just scaled the idea down to fill my room "EQUALLY" with sound.Result,No little sweet spot no,no,no the WHOLE ROOM is the sweet spot now!
OH Bshabaz57 You naughty one ! Sounds like you have quite a great little system assebmled. I would like to hear it. And if one half fails you have backup. Cool.
I have a pair of VMPS Supertower/R's I use as L/R mains in my hometheater....they go woooooof with the best of um. I bought them new 10 years ago.