I have been using a SimAudio 380DSD DAC for the last few years and am happy with it (I preferred it over the Berkeley Alpha Dac 2 at the time of purchase). But, I've been tempted to upgrade and either a used M1SE or a M3 have been on my list.
After all of the good comments/reviews on the M3 I just pulled the trigger on an M3 and hope to get it mid-week. Hopefully it is a step up on my current 380DSD :) I didn't get the Ethernet streamer but if beats my current DAC (I stream Roon and connect with SPDIF) I'll get the Ethernet option.
I'm also tempted to try the DAC direct to my Pass X250.8. I tried the Berkeley direct to the Amp years ago and although the sound was extremely clean and transparent, I ended up much preferring having a preamp in the chain (Sim 740P) as the soundstage exploded and everything sounded more like music. It won't hurt to try direct again though...