Thank you to all, gave me good advices.
I did move the Sub around, but still not help. Finally, from my Reciever 2200 I made changed all my speakers setting into "small" and moved the Sub into the corner wall, but it's not touching the wall.

I found it big improvement to the bass, stronger deep bass.

same question, should I buy another identical EP350 sub???
may be this is a crazy question, but I'm thinking that if I have another sub and I'll be place in the back of my room, do i get bigger bass. Or I waited my monney.

Thanks again for great help.