This dizzying array might seem like overkill, but Sony's premium "Experience Balanced Armature" (XBA) 'phones are carefully targeted at different price points and types of listener. You've got the entry-level XBA-1 containing a single full-range driver. Add a woofer for bigger bass and you get the XBA-2. The XBA-3 also squeezes in a tweeter for high-freq perkiness, while the XBA-4 rounds it all off with a super woofer. Each pair also has a smartphone twin with inline controls, denoted by the iP suffix. Finally, there's a trio of single-driver specialists: the noise-cancelling XBA-NC85D, the sporty XBA-S65 with basic waterproofing for sweat and rain, plus the Bluetooth XBA-BT75. It's unclear when these will hit
