Regrettably, I don’t currently have one of these connected and haven’t the time at present to do so. However, some suggestions:
(1). Simply the change / swap the USB port that you currently have it connected to. (Odd as this may sound, it has worked for me in the past.)
(2). Remove it from the mini completely and zap the PRAM and rebuild the desktop of your OS 9 install.
(3). Then try, try again - booting first with UCA202 disconnected and then plugging it in to the USB port AFTER booting, OR…
(4). After PRAM zap and desktop rebuild, connect it and then reboot. Any difference?
AND, if you’re not getting any sound to headphones via the UCA202’s headphone jack (with no speakers connected) then you might have a bad unit. Test this first, perhaps before any of the above.
ALSO, I don’t recall being able to set volume via the sound control panel before (but this is relying upon my foggy memory from several years ago). AND the powered speakers that I did use had an inline volume control knob where I rather simply adjusted the volume.
There’s also always the possibility that you’ve an extension conflict, if ALL extensions are ON.
And hopefully you’re not using any sort of USB hub?
Okay, update.After an hour digging around here, I found a UF0202 and attached it. No, it does not show up in the Sound control panel and it is therefore not level adjustable (there). However it does play desktop Platinum sounds from clicks, etc. And with headphones attached - the sound level, is adjustable through / to the headphones via the volume dial on the unit.
THEN popped in a music CD and via iTunes, music played and individual tracks were selectable.NOTE: in order for your UCA202 to appear in the Sound Control panel (as I believe the M-Audio Transit also requires) you may need to download and install the “ASIO 4ALL USB Audio Driver” from the Behringer website.
Good luck.