Title says it all, I'm wanting to get a pair of Sennheiser HD800's and I currently have an Apogee Duet2 hooked up to my Mac Pro as the source for my HD650's. Previously I have owned a Lehmann Rhinelander headphone amplifier which I used in conjunction with my current setup and only noticed a very subtle difference from using the amplifier in the Duet, not enough to warrant the extra cost, so I sold the Rhinelander.
People often say it takes a lot to drive the HD800's so I would like to ask whether the Duet2 is good enough, and if not then why? Please be technical if possible, what precisely about the Duet2 isn't good enough?
Thanks in advance guys :)