A Tidal HiFi subscription is a good place to start. Barring the $20 a month fee, just feed it the highest resolution files you can afford. The M-100 are more resolving than people realize.
Use software that won't use Windows resampling so you get bit-perfect playback. foobar 2000 or JRiver Media Center will allow you to do this, although there may be others I'm unaware of.
Here's a crazy one. Get this cable. You don't have to do it right away. Spend some time with the M-100s, get to know how they sound, and if you start to yearn for more you can try a $19 experiment. I have a detailed review of the cable here.
Sweet, thanks for the heads up. Something somewhat unrelated - I installed the XL Pads on my V-Modas and they seem to all be snapped in placed, I can see the retention clips, but some of the leather is warped around the clips. Normal? They seem to be held in place just fine.