wizboy, I have a set of akg 240s and Dave is right about the low volume but he got his ohms backwards. the standard 240 is a High impedence (600) which does give low volume unless well amped. Akg has just released a Low impedence(55 ohms) version called the studio 240 which will have a much higher output.
The sennheiser will have better isolation and less leakage in a recording situation.
I also like the sony 7506 very much.
Bill E