Shortcut or badcut?

I highly doubt this will accomplish your goals and will likely create more problems than it solves.  It would help greatly if you would share what equipment you’re currently using along with a bit about your room and speaker positioning. 

It can be done, But..

Generally to accomplish doing so and getting it to perform and sound worthwhile will require 'pro sound' equipment of the sort you see at concerts. They have a whole range of devices and means to make those arrays 'do what they do'...*S*

@mijostyn has your best option, but level and balance control over the back pair (at minimum...eq added to that is a plus) would perhaps fill the bill for just sheer volume.

No guarantee as to what you may hear, however...*shrug* 

I am quite happy with the sound I have, so I will take the given advice and not mess it up with a dumb idea.  The SuperTweeter seems like the way to go, so I will $tart $aving.

Thanks for the info.  Much ....appreciated.

You will lose your sense of sound stage.

OP... What is your definition of "air?" Is it to increase the high frequencies, meaning more high-end extension? Or are you looking for the phenomenon of air around the instruments? This would increase the space surrounding each instrument and improve focus.

If all you want is more high-end detail and extension, then super tweeters are worth trying. For true "air" in the audiophile sense, then it's more complicated.