What you may want to look at instead is something you can put the TV on with room for the center speaker underneath it. IKEA things that I have seen are pretty flimsy and not good for supporting a lot of weight.
You would have to check your budget and dimensions but maybe something like this?
http://www.overstock.com/Home-Garden...?sec_iid=33969
The back panel is usually two pieces- I left off the top portion on mine to allow access for cables and air. I actually have a Mission style Buffet I got from Overstock for mine (your speaker would not fit in it). That would help your speaker sound if it is open and not closed in back. These come unassembled but should include keys (tools) to put together. They still charged me their basic $2.95 or whatever shipping. (ordered a couple years ago).