I always have all three clients synchronized, even when I’m listening to just one – I turn the individual outputs off through the downstream audio amplifiers. Similarly, I always have the hard disk connected so haven’t tested the use of just one PSU. I can experiment with this, but the dropouts are very stochastic – I’ve had no problems today, even though I’ve been listening since 6am. It’s also possible that the interrupts of the internet stream are different from those I get from the hard disk.
I can’t believe that this is connected, but I normally play my music in Random Song mode by genre, and the CPU load is around 20% with the temperature at ~60C. Today I’m playing individual albums (currently Ziggy Stardust) but the CPU load is only 6% and the temperature is 53C. I probably need to collect more data points before I construct a hypothesis around this….