Stereo to HT, whats the best way?

In all of your humble, yet knowledgable opinions, what is the best way to add channels to a 2 channel set up for quality 5.1 HT? You've got $1000-1500 to play with, and you want to keep your stereo integrated amp as is, to still benefit from music in stereo. You already have the center, surrounds and sub.

Enlighten me, please!

I would need to know more about what you are currently using because it sounds like you want to keep that and just add-on. In order to do so it's vital to know what you are currently working with in order to integrate the right pieces to make your system 5.1 ready. What type of components and speakers are you currently using?

Without knowing what you own, it's difficult to make specific recommendations...but here goes -
You definitely, absolutely want 2 things:
1) An A/V receiver with pre-outs...this allows you to connect your integrated amp, basically as a power amp for HT purposes, but when playing music, keep your CD/turntable connected to the integrated.
2) A matching center channel. The easiest thing here is buying the manufacturer's recommended center channel for your speakers (if possible). Otherwise you're looking at trial-and-error to find a suitable match. Not impossible by any means, but obviously more difficult.

From there you can consider adding surround speakers. Ideally, these will be timbre matched to your front mains and center channel as well, but if there's one short-cut you can take, it's here. Don't go too cheap or you'll wish you hadn't, but a decent pair of small bookshelf speakers of any make should suffice. Again, if you can, get the matching surrounds - another pair of your front left and right speakers...this is optimal.

Once this is complete you can consider adding a subwoofer...If you're a bass-head, you might want the sub before the surrounds. Up to you. Though it's not really surround-sound without surround speakers.

On a budget of $1000-$1500, the used market is going to be your friend, I suspect. Start looking at audiogon.com and ebay for the right models.

Another good question would be, does your integrated have a preamp in or some other type of processor loop. If not, it isn't going to be possible to tie both HT & stereo together.

You could end up doing what I'm doing now which is having 2 separate systems that share the main set of speakers. My preamp does have a processor loop but my stereo amp and HT amp didn't mesh together sonically. So now I just manually unhook or hook up which ever speaker lead I'm needing for the application I'm about to use. The switch is easy if you use Banana plugs.

buy a dvd player and a multichannel receiver. your dvd player's digital output can be connected to your receiver's digital input. your reciever's main left and right pre-outs can be the input of your pre-amps' left and right input