So the sextett is a AKG 240 headphone? Haha.. my bad, thought it was an amp.
I am listening now using that same AV710 audiocard and I must say I am very impressed, I'd like to say in love. I reallly believe 240 DFs are as good as Ety ER4S. They have perfect midrange and highs, I can't hear much bass though and they sound a bit distant now(until I get an amp). The music just flooows so gently and so detailed, I get to hear everything, I can see now what Wolfson DAC can do too, AV710 sounds a lot better than audio cards at $40 price. A soft mood is so present within me (I listen to instrumental music mostly, also Jazz, Country and New Age). Listening to Ronan Hardiman, the CD has never sounded so good after I last time listened to it on D311 and Er4S. I have Senn HD497, PX100, Koss KSC75, KTX pro 1 and a couple pairs of not expensive inear and they don't come close to 240 DF even combined and even with such an impotent audiocard. I can't wait for my amp to arrive now.
P.S. I also appreciate the design of the 240 DFs, vintage... I love the look.