Mixing 4ohm and 8ohm

Interesting! So if I went that route I would assume all 2 channel (turntable and CD)would be powered by the stereo amp but would be controlled through my AVR? 

I was working with an upper end Yamaha that was paired with 4 ohm speakers.  The Yamaha doesn't have a "4 ohm" setting, but it does have both 8 ohm and 6 ohm settings.  The speakers just did not sound good on the 8 ohm setting and sounded much better under the 6 ohm setting.  Most of these low impedance speaker problems have to do with the amplifier power supply and amp circuit.  Some of these just don't have enough brute force in the power supply to be able to push enough current for low impedance speakers.  I suspect these receivers are switching a 2 or 4 ohm resistor into the output load of the speaker binding posts, therefore increasing the load a bit higher so that the amp power supply / board has an easier time driving the speaker load.  Like Erik said, the result is a little less power output because you are now splitting power between a 2/4 ohm resister and the actual speaker, but the sound quality should improve.

Imhififan's suggestion of an outboard amplifier would solve your problems.  You could even look into a beefy 3 channel amp if you wanted, to drive your entire front stage.  In HT/movies, the center channel is almost the most important speaker.

So if I went that route I would assume all 2 channel (turntable and CD)would be powered by the stereo amp but would be controlled through my AVR?

Yes.

I'm upgrading my home theater front speakers, which will be used for 2 channel music as well,

You also can upgrading 2 channel playback by adding a stereo preamp (with HT passthrough) to your system.

Suggestions on a stereo amp that would work well with Leagacy Signature speakers and my current Marantz 7010 AVR? Would like have enough power to open up those speakers but not break the bank.