I replaced my KA6 with a Roland Duo Capture Ex (also USB 2.0) and haven't had a single pop or drop-out since. The KA6 is not the only interface where USB 3.0 compatibility issues have been reported (I've heard similar complaints about Steinberg's UR22), but it's definitely not an across-the-board problem with USB 2.0 interfaces. It's also worth noting that not all USB 3.0 chipsets and drivers are alike, since the technology is still recent-ish and some computers were released with "USB 3.0" support before the standard had been fully ratified and adopted. I know that the Roland interface works wonderfully on my laptop's USB 3.0 ports whereas the KA6 definitely did not. But there are probably people out there who might never get a USB 2.0 audio device working on their system without BIOS/USB/chipset updates on the PC side, not just audio interface driver updates.