Driving a good pair of speakers with any part of an AVR if you care about 2-channel is just silly. SILLY. And, as you'll see below, completely unnecessary. It's like buying a Ferrari and putting Sears Roadhandlers on it. Sure, you can do it and you still might get some enjoyment from it, but most of the performance you paid a lot for will go unrealized. You can patch in a good amp through your AVR preouts and that'd be like replacing the rear tires. Yup, you get to enjoy more of the performance, but you're still leaving a crapload of enjoyment on the table. Not until you replace the entire AVR in the 2-channel chain with a good stereo amp and pre (and assuming you have a decent source of course) will you get full enjoyment out of good speakers. And you CAN replace both while leaving the AVR in for TV/video purposes. Here's how...
Since you have preouts on your AVR, you simply take the front L/R preouts and route them to an unused input -- let's call it "video" -- on the dedicated stereo pre (or its HT bypass if it has one) and connect the stereo pre to the stereo amp as usual, which is then obviously connected to the speakers. (Same can be done -- even easier and likely more cost effectively -- with an integrated stereo amp). Your high quality 2-channel source goes directly into another input on the stereo preamp or integrated -- let's call that input "CD" -- and you're basically done, and now the AVR is completely removed from the system for more serious 2-channel listening. When you want to listen to good stereo you choose the "CD" input on the stereo pre, and when you want to watch TV/video you choose the "video" input and that's it. The only thing is that if the stereo preamp doesn't have a HT bypass input you need to set a reference volume level on the stereo pre that is balanced correctly with the AVR. I used to just use the 12:00 position on the pre as it's easy to set quickly and fairly accurately.
Lots of us have done this here with great success, and trust me it's much easier in practice than it looks here in writing. You'll now have a pure, high quality 2-channel system seamlessly embedded within your video system. Best of both worlds! And you can do it in stages as funds allow and fully appreciate the significant upgrade each stage brings. Of course then you'll want to upgrade your speakers again and on it goes...