I'm still breaking in the 65th anv but listened to them briefly tonight and switching from the K701 to the 65th showed a clear volume difference so I broke out the SPL meter and measured. Playing pink noise and with the volume set to generate 70 dB on the K701, switching to the 65th shows 72 dB. Pretty clear these are not the same and even though they have the same impedance and efficiency specs the 65th anv is much easier to drive. I've always felt AKG's efficiency specs for the K701 were garbage anyway.
They also do not sound even close to the same to me. I'm not sure how I feel about that yet as I actually bought these because I wanted a more comfortable K701. My K701s are about 5 years old and I've never heard any of the other models so I'm wondering if the newer K701's are different too. I know the Q701's are supposed to be and I'm actually tempted to buy one just to experiment.