Can I move my TV down?

Well, you aren't going to like the answer.

Technically, you can move it wherever you want, it just depends on how much work you want to do.

I would put the speaker on top of the TV, and put the tv further down.

Just me.

What is the make and model of your speakers? Why not use a "sound bar" shaped center speaker? It might only be about five or six inches tall. Mount it "in wall" or "on wall" just above the top piece of equipment. Check out something like Definitive Technology's Mythos Ten to see an example.
You could pull the TV all the way down and then mount the center above the TV.

My advice will always be not to half ass anything and call it "good enough". Do it correctly.

If you are happy with "good enough", so be it. If I'm spending the money and I can control quality with my own labor, I'm going to make it 110%. Not everyone is as anal as I am. Set it up the way you want, listen to it. If it doesn't sound right, you can always rip it apart and start over, right?

That's the biggest issue with in-wall & in-ceiling speakers - you can't control all the variables and are often stuck with less than perfect installs from the fact that you don't want to tear it apart and do it over to make that little difference you can get from just pointing a standard speaker slightly differently.

If you try it and hate it, you can always change it. If you try it and it's ok, then don't lose any sleep over it.

This is what happens when things are done backwards.

So you're going to buy a fancy very expensive speaker and then you're going to cover it up (partially)? Sorry, but this is just too funny.

I would not move the TV down any more. As a matter of fact, even in its current position, it may be affecting the sound because the speaker will be behind the TV and not flush with it.

And just curious, how big is the TV and how far away from it is the sitting/viewing area?

Dolby says place the center speaker below your viewscreen, and you side speakers centered on either side of the screen.

THX says you can do below (lowest quality), above (better quality) or behind the screen (best quality, but requires an acoustically transparent projector screen).

Check Dolby's Site and THX's site for more information.

I went somewhere in-between the 2 recommendations when I set up my 7.1 system and am very happy with it (since i prewired with CL-2 in wall wire, that's a good thing!).

I'm not so sure about the speaker being almost as big as the TV, however.