Unfortunately I can't say; definitely possible. I never use electrolytic caps (except in heater supplies) so I'm no expert here.Hi Mike
Thank you for this indiction. One point to add, this morning I turned the dac on and it is working fine but I only played one song. Yesterday it was working fine too but after 1h or so the noise started. Apparently this issue manifests itself as the dac warms up, could it be? later today I will seat to listen for a couple of CDs and see if the issue repeats.
Could this still be linked to the electrolytic caps?
Intermittent problems can be very hard to find.
With it playing music OK, but with hum, I tend to think power supply but I could be wrong. Problems in the circuit itself usually cause things like no sound at all, crackles or nasty noises; hum tends to be the power supply. But not always!
And just possibly, a bad joint at a rectifier diode might cause such a problem, and bad joints can cause intermittent problems. Some kind of earthing problem might cause the hum, but usually that happens from new due to bad design (yes, I've done it myself) rather than fail after running well.