Originally Posted by h1a8
I had both s739 (same sq as s639) and X. I liked the sq of the 739 better because it was louder and had more natural bass. The X's bass is a little rolled off and the clear bass setting makes it sound unnatural. The clear bass for the 739 was perfect. Many think the X is clearer but I say it isn't. The 739 is just as clear. The bass roll off gives the X the illusion of being more clear. I tested with Ultrasone HFI-780, shure se530, and JVC FX-500.
Oh well, compared to my s638 the x-series was kind of clearer overall.
Tbh, the s638 has a bit much bass if I use the Sony MDR EX 500 (bass set to 2 cuz Im mostly using Phonaks)
Im more a fan of clear and crisp sound so I used the Phonaks on the X-series and it was better than before, like from 100% to 120%