When looking for a new Head Unit do i need to choose one with audio 6 channels to accomodate the tweeters and four speakers in my KL?
This information is not always listed with head unit details. I see descriptions like "2 channel stereo" and "6 channel audio pre-out" ?

To answer my own question, I believe the tweeters are on the same channel as the front speakers, hence only 4 channel system (front/rear/left/right).
I'm being told that most head units are four channel unless otherwise stated.

You are correct

With the speakers unless you get an amp the pre-outs aren't really to worry because you just run off of the stock wiring. If you are running an amp, Then it is what matters because speakers go into the amp via speaker wire and then RCA's into the amp then into the headunit.

But you are right, Front tweeters are connected usually by a cross over then it is one set of wiring (component). then the rears have them in the speaker (coaxial)

With the speakers unless you get an amp the pre-outs aren't really to worry because you just run off of the stock wiring. If you are running an amp, Then it is what matters because speakers go into the amp via speaker wire and then RCA's into the amp then into the headunit.
Thanks for explaining that. I've just used the existing OEM speakers and using the basic outputs from the Alpine. I notice it has a bunch of RCA's on a dedicated socket, but have left that empty.

I think the speakers are not fantastic, especially the rears, but the sound is perfectly acceptable to me for talk-back radio and pop music to drive by. I did fiddle a fair bit with the EQ settings, like WIDE, frequencies for bass and treble and the balance before i was happy.
Actually, i think the speakers in my KH may be a better quality!

I can turn the sound up pretty loud too without any obvious distortion, so cant imagine how loud an amp and decent speakers would make it in such a tiny space!