want to build a 2 channel system where do i start

Good advice from Veroman - don't lead with the chin. I would add, start with the speakers. Narrow your speaker selection to a few models. I would not limit myself at the outset here - consider floorstanders, monitors (maybe with a sub) - also give a listen to the traditional passive boxes, actives (speaker and amp matched in one box), planars, etc. Then look at the amount of power you will need to drive the different models that you have narrowed to, at the listening levels that you want, in the room you are going to be listening in; that will be your biggest initial concern as to an amp - preamp / integrated. Sources I would look at last. Amounts to spend are kind of fluid, but with a 20k budget, somwhere under 10k for the speakers would be a starting point. Also, quality vs price do not necessarily go hand in hand, especially with speakers which will depend a lot on your personal tastes. You may find that you will be able to put together a system that you are happy with for much less than 20k as opposed to a more expensive system. Probably the best advice I could offer is 'patience' - take your time.

thanks everyone for the advice as i am new to this hobby and dreatly appriciate the input

I'd start by listening to speakers. Find a speaker you like, then find out how to power it, and the rest just falls in line.

I just spent a little less than $15K on my new system. I did pretty much exactly what these people suggest. I listened and listened and listened. On the fist day alone, I think I went thru about 10 pairs of speakers and about 5 amps in just about every combination of them.

The difference was greatest in the speakers and that's where I spent most of my budget, $6.5K. I didn't want many components and went with an integrated at $2.8K. So you can see, I followed Mordante's advice and spent the bulk on the speakers.

The rest was spent on a CD/DVD player, cables, stands, and a power regenerator.

With your budget, you should be able to buy a highly musical system that will play classic rock like a champ!

Consider a horn system for rock about as good as you can get, check out Audiokenesis. KCS loudspeakers, Edgar horns. Bet they can help you select amps etc to go with the horn systems plus some of these guys will do some custom work custom finish, designs etc.