When I was A boy, I had a SHARP tuner/cassete. I also lived up a mountain, where I could pick up radio signals from europe. The unit had four speaker outputs. It was called MATRIX. It was not quad, it was somthing else. The rear speakers which were mounted approx twice the distance from the fronts. Had a little reverb, giving a surround sound effect. When the BBC broadcast a live event, this was the best sound quality we could get. (no recording). It was a sensational event, bringing my mates around to revel in the sound. Theres nothing wrong about rear speakers.
Wanna take it to the next level? Buy MORE speakers!
Did your two speakers take it to the next level? No, they never have and they never will, my friends.
Buy more speakers.
You will be happy because you will be placed in a cocoon of sonic nirvana, taken to the next level.
Sales guy will be happy because he will sell more speakers.
Everyone will be happy, it’s a win-win.