I am looking to upgrade my stock stereo in my 2000 tj. I dont know much about audio in cars. I want to upgrade my stereo to a little more kick. Do I have to have an amp or do some receivers have them built in? Im not looking to install a sub really.
Is it possible to do a decent upgrade with just a new receiver and new speakers? Any suggestions?
You can liven it up with a new head-unit and speakers. You will increase sound and clarity. You will want to upgrade the front dash speakers to 5.25" with the proper adapter plates.
Running aftermarket speakers off the head-units internal amp will work, but you won't be getting the sound you would with an amplifier.
Listening to music without a subwoofer is like hearing in 2D. Adding a sub will make any kind of music liven up and add a whole new dimension.
It is possible to do anything, however if that will result in satisfactory sound to you, only you can decide. That said, it's pretty much impossible to answer your questions, since we're not you.
You could try doing it in stages, good head unit, good speakers capable of low power (35W RMS or less) running only off the head unit, then plan to upgrade later if you need more power. Though then that would require new speakers again but you could sell the old ones to recoup cost.
If you need more low end, then a sub and sub amp would be required.
If you can't take a nano-second to press shift/period/etc. and make proper sentences and paragraphs, I don't know if I can take a few minutes to respond to your topics... It doesn't have to be perfect by any means, but a little effort goes a long way.