Ibasso DX 320 , Amp 14 is an excellent upgrade, Tube vibes all the way! I have had No negative issues with this AMP, and the improved Headphone plugs, Nice!!
I love the sound the DX300 produces with AMP14. However there is some faint noticeable ringing and EMI that I hear from time to time during quiet moments like skipping songs, connecting headphones /IEMs. I'm certain the AMP14 card could have benefitted from additional shielding. All that aside, AMP14 adds a very appealing flavor to the sound of the DX300.
Sound is more natural, tube-like, and dynamic, but the big plus is the interferences from Wi-Fi and movement are much reduced - not eliminated, but no longer bothersome.