It seems to me that you didn’t have any problem then using Pico on battery so here some trouble shooting you can try with that in mind. People that don’t “believe” that cables and the right phase matter just skip this post please.
· Are your setup (computer, dac and amp) connected to the right phase? It is very important if you want to get the best sound. If it’s not the bass will sound soft. If a European Schuko outlet is used you can easily invert the L and N lines simply by inserting the plug into your symmetrical outlet the other way around and listening for the best result.
· If you have a US outlet: sometimes the wall socket's internal electrical connections are reversed. It is important to ensure that this is not the case. You can test this with a receptacle tester from your local electronics store or by trying another outlet.
· The computer, dac and amp should IMO be connected to the same phase and power strip.
· The output from the computer should be on 100.
· Check that the clip protector in your media player isn’t selected.
Here are some other things to consider:
· If you have a cheap plastic power strip it can infect the SQ, especially the dynamic.
· The power cord that you get with the M9 or other amp and dac’s are IMO not that good. Kingwa recommend a “suitable power and signal cables”.
· Try to listen to music late at night to control if the bass is soft when as well. Usually the power grid is more polluted during the days and evenings.