I've had my Micro Amp/Dac for 28 months now with mostly daily usage of 3 to 4 hours. To be honest, the SQ, while still clear and well defined was getting, at least to my ears, sort of flat and ummm, tired. Don't remember the 'stack' sounding this way when I first brought them home either. I replaced the power brick that came with the Micro Amp yesterday with the Astrodyne power supply. An impulse buy for sure but after listening to the stack with the Astrodyne powering the Amp, the SQ improvement was very obvious and immediately apparent! Now I'm wondering if the Mirco Dac's power brick is in the same condition. Do power supplies wear out?
Yes, electrolytic filter caps do wear out after awhile. Even the best ones. The good news is that they're inexpensive and easy to replace. (You will need to know how to discharge them, their polarity and how to solder, though.)