@rastus: The Sbooster pic shows a very ordinary design, with a line filter, a (very) cheap toroidal transformer, and a simple rectifier and filter, absent any of the parts normally used in a good audio power supply. It is a good, basic, linear supply made with inexpensive parts, in a plastic box, with a simple regulator on the output, single sided circuit board, and inexpensive bulk capacitors.
I also see no mention of a shield in the description of the transformer, which would be a requirement for a high-end custom toroidal audio transformer. (Compare pics with the one posted above by someone else, showing a transformer made by Talema)
Again, this is a VERY basic, VERY inexpensive supply, the rest is just marketing.
An improvement over a switching supply, to be sure, but NOT a high-end audio-grade linear supply at all.
Btw, there is no such thing as "polluted" current and "purified" current. You can filter high frequency noise with the line filter shown in the pic, but this does nothing else. Any noise which is actually in the audio band will pass right through the line filter.
An example of this is an old refrigerator in the house where I am now staying. When using a simple wallwart supply, or a 5V power brick-type supply, I can hear the noise on the output using a headphone amplifier and a mid-price pair of headphones. However, testing with a bench supply, the noise is gone.
This is something you can try with the power banks, b/c you can unplug them from the wall outlet... and one of the things I had in mind when I started this thread,
by rastus » 13 Apr 2016, 00:39 
