Ok I tried Ananda, Sundara and Deva today, each one I listened to more than half an hour. I don't have a portable amp so I use my iPad to drive them directly (also tried BT with Deva):
1) For my ears Sundara doesn't work, it's too short. Deva works better, the internal of pads are in olive shape so my ear can fit in but I can still feel the pads. Ananda works best for me.
2) I can drive Ananda with my iPad and get acceptable loudless and SQ, I have to max volume though. Sundara works but the volume is very low. Deva is the loudest, however the SQ is the worst. Strangely the BT connection for Deva provides far better SQ.
3) Sound wise, Ananda is more analytic and "cool", bass is deep but the amount is a bit lacking. Sundara is warmer, the bass is a litlle more than Ananda. Deva has even more base but the piano doesn't sound like piano when I play Rachmaninoff Piano Concert no. 3. For all other music types Deva is actually quite good. I can't match the volume so above just my subjective feeling
So conclusion, I like the Sundara's sound most, it is very simiar to Ananda but warmer. The two headphones are very close in terms of SQ and I prefer them to HD660S. I'll pick Ananda when it's on sale mainly because 1) it fits my ears better 2) it's easier to drive so I can listen to music in bed with iPad while watching news etc.