I Tabness thank you for your response- this was for me interesting and useful than some of the previous comments that failed to compare the sound signature. It’s a pity Sony haven’t considered re-launching the R10 drivers in a different housing. Sony has done considerable research into biocelulose drivers in the 1980s. Some of their upper echelons of speaker design have been Japan only speakers (SS-GR1 & SS-G777E and SS-A5 all use biocellulose tweeters). Fostex (TH900) and Pioneer (SEM5) amongst other Japanese companies have current production headphones with bio cellulose drivers, so it’s strange Sony haven’t returned to this material. My own considerable experience with TH900 (owned since 2012) has left me with the following thought on their drivers. Despite other flaws (v-shape signature, slightly hot treble) their drivers are extremely musical and I have had some emotional “peeks” with music I’m familiar with. I’m not sure why, but in terms of connecting me with certain songs (whipping post by the Allman Brothers - amazing IMO with TH900) these drivers have something special about them. I’ve listened to the same song with HD800, SEM1, AKG712, Z1R, Z7R, and none of those headphones have connected me in the same way to that particular song. I’m talking about feeling the raw emotion behind the song, the guitar rifts are well known as being epic. Having said that I’m not suggesting the R10 & TH900 are similar in sound signature - having never heard the R10.