One of the things that's been increasingly bothering me about the LED clock setup is a constant high-pitched noise emanating from the LEDs. It's something I can hear from the other side of the room if there's no music playing. A bit of googling quickly pinpointed that this is commonly due to the driver chip doing PWM to the LEDs (PWM is the way the brightness of LEDs is controlled). I experimented with different brightness settings and found one that has very little audible noise (at least to my ears), so all good for now, but something to keep in mind.