Galapac
1000+ Head-Fier
The FiiO M15 is my main player and I will either listen to it portable, and with VC or VO you do not even need the over-ear headphone mode or high gain turned on as it gets pretty warm, or I use an USB to USB-C to output my FLACS or TIDAL/Amazon Music to a tube amp. Very versitale player. With the dual AKM AK4499EQ chips you cannot go wrong and gives A&K players a run for their money. Great pairing!Running my Olive VC Portably via a Fiio M15 and it absolutely sings, despite it not supporting Apple Music, I still have a good portion of my Library in FLACs and my free Tidal Hi-Fi sub and at a Volume of 60 it gets pretty loud 70+ begins to hurt my ears. I don’t think the dx300 is as Powerful as the M15 Spec wise, but It should be able to drive them reasonably well, not only that it probably feel smoother due to the faster SoC.
One tip: I added a clear velcro strip to the back so I could mount it to a shelf when using it next to my chair for easier access while being out of the way. It's still built like a tank though!