I've said this before, but since then I've upgraded my opinion of of the AV710 based on additional burn-in and/or better setup. So, I tried a head to head comparison again and my preference is still the 39x0.
My comparison is based on the following setup:
3960 -> JMT CHA47 -> CD780
AV710 -> JMT CHA47 -> CD780
listening to Christopher Parkening Plays Vivaldi, Warlock and Praetorius
The 3960 sounds smoother, yet is still very detailed, the music is deeper with better presence, imaging and soundstage.
I also have a 3950, but it's not so easy to move it around to do a head to head comparison. The 3950 has a slightly better display and it is very close to the 3960 in sound.
[One thing in the AV710's favor, if you have efficient headphones, you don't absolutely need to have an amp, I usually use the HD280 with it ampless.]