The E5000 needs a lot of juice in low-imp mode. Most portable DAPs don't do that. M0 will be very inadequate, same applies for the R3 Pro (though via balanced out you'll be less disappointed).
After nearly 2 years of going through various sources across various price points, the cheapest DAP that's fully complemented the sound of the E5000 was Cowon Plenue D2 via the 2.5mm out. Currently I'm using the Plenue R2 and it's the best pairing with the E5000 I've heard till date. Will post a detailed impression later. Other DAPs that had great pairing: Questyle QP1R (medium gain) had great dynamics but the bass would become too much at times. Cayin N6ii + E01 was the most lush pairing that didn't sacrifice details and still had fantastic bass control but it's TOTL level and a bit of overkill for an otherwise midrange IEM.
It's fun, V-shaped tuning. The Adagio II was too much bass for me, Adagio III fared better but I personally prefer the E3000 at that price range over both of them (or the Heaven II if you want more textured vocals).
Should I just buy the E4000 then to pair with my Shanling M0? Is it much different from E5000? I really want a cable-down type IEM.
Or are there other options?