Thanks for the tip, I've had neutron for years. It's great.I would suggest that you give Neutron player a try too if you haven’t already.
https://neutroncode.com/
Although I do not own the DX340 to give you a fair comparison, I find Neutron to sound better than UAPP on my Sony Walkmans(multiple). I find Neutron to have a more calibrated smoother dynamics compared to the more upfront aggressive sounding dynamics of the UAPP which makes the Neutron player more pleasant for long term listening fatigue.
Neutron player has tons of advanced adjustments(like dither, filters, floating point calculations) that can be done to shape the sound even further.
It is paid software like UAPP but there’s a free evaluation period to decide if you like Neutron enough to purchase. Do note neutron is mainly an offline player.
However, I can't use it now because I'm stuck with tidal (offline too of course), and neutron doesn't support it. I don't know when I'll rebuild my local music libraries.
(latest YT review)