[W9TR]

Here is an article that succinctly defines the problem with line operated switchers.

https://www.eetimes.com/power-tip-47...chers-part-1/#

It is from 2012, btw, so this phenomenon has been known for quite awhile. I believe it is the same mechanism John Swenson describes on his website.

In my case there is no path to create any such currents. My battery powered tablet floats wrt to everything and any common mode leakage currents it might impart to my Yggy would be based on an external signal coupling through the air to the tablet’s 14 pF free air capacitance. I have removed all nearby radiators so that’s not an issue.

There are other noise sources. For example the USB power coming from the tablet might be dirty. That noise is not common mode, and not referenced to any grounds in the Yggy, so does not have a path into downstream equipment.

There could be noise from the onboard WiFi transmitters. I don’t have a way to measure this directly, but I have run some comparisons with WiFi on and off while streaming content from the tablet’s SSD. I can hear no differences.

The notion that tablets or laptops are intrinsically inferior to dedicated end points is simply not true. The answer is ‘it depends’ and there are a multitude of interference sources in play when you connect any digital device to your lovely analog stereo system.

When you hardwire your mains powered endpoint to any DAC, you have a multitude of interference sources to mitigate. I think Uptone is doing a fantastic job building effective products that mitigate this type of noise.

This is the frontier of excellent digital playback and deserves more airtime.

Tom