Disclaimer: This pair is owned by Flysweep, who generously let me borrow his IEM for a full month. I truly appreciate your contribution, my friend.
Sony XBA-30 is a revised version of XBA-3. As there isn't much to complain about XBA-3's original performance, the question is: What has been actually "revised" from its predecessor?
CON: THD is actually worse, reaching 1% @ 1 kHz : 100 dB SPL, along with the misaligned channel matching.
ON SECOND THOUGHT #1: All the other factors are totally identical to those of Sony XBA-3. Please refer to XBA-3 for further details on modification / effort for improvement.