Then M500 is outputting 4V I guess.I had weird experiment recently.
I tired 2 DAC to power SA-1, SMSL M500 & Singxer SDA-6.
The M500 should output 6.8V and SDA-6 only 4.6V, however the sound volume is much higher with SDA-6 even it output less voltage .
I recorded a video and I will upload it later to show the volume change when I switch manually input ( only XLR ).
What could be the explanation?