Don't forget to look for a maximum of 2 vrms to avoid cuts. I have it with the fiio taishan d03k that gives 1.5 vrms. I bought and the smsl c100 quw gives 2 vrms which is the maximum of the fosi to use the entire volume of the fosi. I tested it with a fiio bta30 which is 3 vrms and trimmed with half a knob. It worked horrible, if I turned down the DAC, which can be adjusted with a knob, the audio was not of good quality. That's why I use the fiio taishan while the c100 arrivesThat makes sense. I was testing with a cheap Mii Bluetooth receiver that has no Vrms output specs. My plan was to use an iPhone with a ligtning to 3.5 dongle as a source. It's supposed to put out 1 Vrms with higher than 300 Ohns loads, which I guess any amp input is a lot higher than that. I'll see how this plays out and look for a proper DAC if not satisfied.
Thank you, @GXAlan!