I have bought the latest qc20 black and blue ribbon for $299. I also have the older version (black and grey cable). I want to report that the sound quality on the latest sound much better.
1) the sound is much more richer, with slightly better mid range than the old version.
2) there are an increase in overall bass level .. Up to double that amount. The most noticeable is the sub bass, the bass sound like their speaker system. It goes much more deeper than the old version.
3) treble is slightly more smoother. The older version might have a little more treble as it sound thinner.
Overall, the sound quality differences is not small, this is no cable change type of small differences, it's like another headphone with more bass. The new one still has that Bose house sound but it's really way better than the old version. For $50 more, I urge everyone to get the new version.
The sub bass sound similar to se846 type. Of course, this is no se846 sound level.. Not even close. But I am saying their quantity is similar not quality. I compared to my jh Angie, and I was pretty taken aback that the bass level of Bose is around 2pm on my Angie bass dial.. The Bose has more sub bass presence. Of course, the Angie is at another level, just using another example.
To be honest, when up in the air, the Bose sound really good..