> do you think it's good idea to put two more panels behind speakers (not directly behind but close to the gear stand)? <
That's one of the last places I'm concerned with because your speakers don't face that way.
> I already have panels behind my listening position which is 3 ft from the back wall. When listening to classical music, i still hear a bit of echo but not very clear unless i put my mind closely to music..:) <
You could certainly experiment, and maybe putting a few panels on the front wall will help. But if that does help it's probably because more absorption was needed in the room generally, versus needed at those particular places.
--Ethan