I recently reviewed the AKG K612 PRO which offers a better value and improved sound. Here is the review.

Thanks for the review. 990 is available at three impedances - 32, 250, 600. Also, check again; the 990 has clearly a superior sound stage (over the 600). This fact is widely recognized. 

Thanks for reading and commenting. Peoples perception of soundstage is far from factual. I respectfully disagree as an owner of both headphones that the 990 has superior soundstage. This is my subjective opinion, thanks for sharing yours.