It was more than 2 weeks after modifying my Singxer SU-1 with the external DC power supply. I am using I2S interface with the PS Audio DAC.
After some hours of serious listening on mainly jazz & vocal, my sense is there is not only a noticeable reduction of background noise but also find that there is a improvement in all aspects such as resolution and richness of each tone in all the range. (Not sure whether is the running in of the SU-1 or due to the modification or both).
ARC Ref 10; ARC Ref 10 phono; ARC CD9; Goldmund Telos 1000+; Thoren TD550 with Koetsu Jade cart & Plixir PS ; Clear-audio Master Innovation with Titanium cart & Accu drive; PS PW Bit-stream DAC, Wilson Alexia, PS P10 & Sine Gateway 2