Installed new speakers and a stereo. 4×6 infinity kappa 463xf, 6×9 alpine R2-69, and a Kenwood KMM-X705. I fell like the speakers sound disconnected from each other and they don't sound as good as I expected, especially the infinity 4×6.
Will an amp improve the sound quality and the "connection" between the speakers or did I make a bad speaker choice?
Or did I have my expectations too high?
Everything is wired in with harnesses/adapters from Crutchfield

 

Maybe they are out of phase? (polarity reversed on one of them)

You could try reversing the polarity of one speaker and see if the sound changes.

But to answer your question, an amp generally may or may not improve sound quality. If your speakers are out of phase, an amp won't fix that.

 

These modern single din head units are total garbage. I have the same one and hate it. I'm running my fronts off it and it sounds like a single transistor radio, I can't imagine how bad it sounds driving all four. An amp will probably make a difference but you have to make sure all the equipment is matched properly.

 

I can`t say about the amp, or about the speakers polarity. I can say that the speaker wire makes a difference though, cheap speaker wire will make it sound bad, you don`t need to spend a massive amount but definitely upgrade the speaker wire.

 

Had a simalar issue with mine recently. I used stuff I had left over from other projects that I knew sounded great together with out an amp. After install and before putting the dash pad back on and the sail panel covers back on I did a test with to make sure all sounded clear and in phase. It sounded all sorts of not right. So I did a continuity test of each wire with the car off and battery disconeected to verify the polrity of each wire from the headunit to the speaker.

 

Yes. An amp will improve the sound. Provided everything is installed correctly.

 

Car Audio hadn’t taken off in 1982. G body cars had a single speaker in the dash until 1988.

Imagine if the maxell ad guy was seated inches away from the rear speaker on the left and 4’ from the right. Then imagine the front speakers were pointed upward with a mirror at a sharp angle mounted over top. He’d get up and leave.

If you’re considering adding an amp, look at the Kicker Key 200.4.

It has a built in automatic Digital Signal Processor and will fix the crummy time alignment & front speaker reflection for you, as well as set crossovers & generally make the stereo listenable.

https://www.kicker.com/key-2004-4-channel-smart-amplifier