Distance from the front not the rear wall?

You need a minimum of 4 feet and 8 feet is a lot better between the listener and any walls. After about 8 feet it really does not matter that much (diminishing returns).

If you cannot get at least 4 feet between you and the wall behind your head then you can reduce the problematic reflections by putting up some RPG skylines or heavy curtains.

Do not under estimate how bad teh wall behind your head can sound. It can ruin the bass and it will totally ruin imaging and soundstage - the sound will be claustrophobic and fatiguing. Those who cannot hear the deleterious effects of walls near the listening position should seriously consider whether it is even worth investing in high end gear.

You need to treat the wall behind your listening position. I have used ASC products for this with excellent results.

It's best to have the listner away from the back wall as Shadorne mentions. But if you cant then putting the listener right against a treated back wall can be a very close 2nd best. When right up against the wall the reflections are not delayed enough to cause blurring.
I use GIK products for treating the wall directly behind me (aka the back wall).

Yup, the front wall is behind the speakers; the rear wall is behind the listener. It's the front and the rear of the ROOM.
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