Flat Screen Television behind speakers

....+ points for an automatic curtain that plays an HBO-esc fanfare on opening or closing when switching from screen to system or the reverse....defeated if curtain is open when the HT mode is engaged...

Double points if the curtains make the *ssshhh* sound heard at the local moviehaus... ;)

(Oh, c'mon....you've already spent more on 'just ICs'...*G*)

Speakers near back wall is not good either.  Simply putting big absorbing panels behnd them will null the reflections that would arise if the speakers were further from the wall.  But as a needs must, compromise solution that is the best you can do

Position the screen between the speakers, not behind.  This will affect the sound least as there is little output from the sides of the speakers.  But covered with cloth absorbents or not, the large flat area of the screen will block sound transmission around the room, with unpredictable results.

Incidentally, the sub-optimal speaker placement suggests you may have a smallish room.  If this is the case your screen may be too large.  The width of the speaker should not subtend an angle of more than 35º at your head.  This is the maximum width of the high-resolving central area of our retinas.

Having your screen between the speakers is a very good thing: films and TV will sound spectacular. I have a high end system (Vitus Dac/amp plus top of the range Boenicke speakers) and films sounds better than any cinema room I have ever heard.    
The screen makes no difference to my sound - I tried covering it but really it made zero difference. 
Just enjoy the music, and the films! 

I must say I have never noticed a difference. 

My experience is that that the TV is reflective and will smear the sound.  As others have mentioned a blanket over the TV is a good idea but I would recommend this:  Get a custom blanket with a picture of your significant other on it.  Bank the good will gained for future upgrades!  Cheers