I own XBA-30 and XBA-1 but I prefer XBA-1 because of its laid-back nature. I maintain at lower volume on my sansa clip+ (at 4 volume bar on "normal" setting) and I still can truly enjoy the detail it gives. Bass is still punchy and tight although it's under emphasized. The treble....I love it. It is very inoffensive and avoids harsh cymbal crashes and nail screeches of XBA-30. I find XBA-1 is perfect companion when I'm relaxing or studying so the sound would not distract me. However, If I cranked the volume up, its sound really hurts my ear, like the sibilance thingie? It's hard to describe but I think XBA-1 is made to be heard at low volume.
I find more improvement from XBA-30. Sound spacious, extended treble and impactful bass. The mid is still mellow and sweet like that XBA-1. BUT the treble kills my ears when it comes to cymbal and hi-hats screeches or anything that sounds tssstsss tsss. I thought XBA-30 has fixed the metallic sound from XBA-3 high but I'm surprised that the treble still offend me. I can't think how painful the treble coming from XBA-3 is. Its sound can be exciting at first, but it fatigues my ears more quickly than XBA-1. It just reminds me of klipsch S4 which I dislike for harsh yet sibilant treble ( and focuses on tsss tsss sound too). I wish the treble would bring more focus on the vocal and guitar sound instead.
More importantly, XBA-1 has the edge because it isolates far better than XBA-30 due to its barrel shape instead of the "vertical" shape of XBA-30. XBA-1 and XBA-30 must not be paired with the stock tips because the sony's hybrid tips have tendency to suck one's ears REAL bad when inserted deeply then removed. I use V-moda vibrato medium tips and it isolates significantly better, even more than W4, klipsch x10, and UM3x. Meanwhile, XBA-30 can be paired with Gr07's hybrid tips, which look like sony's, and they're less prone of suction, much comfortable, and has bigger bore than the sony. I suggest to use the purple GR07 hybrid tips, which is extra large, to avoid the splashy treble XBA-30 gives.
I bought XBA-30 for $130 from one of head-fier here, and I'd say, neither impressed nor disappointed. I'd be disappointed if I paid full price for $180 on ebay/amazon.When I first had XBA-1 for $48 from best buy clearance, I was greatly disappointed . But, it took me around 2-4 months to start appreciate its sound and I even prefer it even more than the more priced IEM I have. So, I believe this apply to XBA-30 so hopefully I would love this IEM just like XBA-1 in the future.