The treble is not harsh at all for an ESS device.
My recently acquired Qudelix Bluetooth LDAC dac/amp gives a less forgiving treble sound profile.
My e1da 9038s does a similar good job of having less a harsh treble on a ess implementation.
So far it feels like the Dx220_max has a nuetral-to-warm sound to it. Lower mids are also thicker sounding with more impact. Treble is forgiving and it layers the treble to the rest of the sound better.
The 9038s Gen 3 usb dac/amp being nuetral cold. That has cleaner bass representation. And a cleaner treble presentation, but unfortunately the treble is on the same competing plane of sound as the rest of the spectrum. Has more of a intimate sound; especially for voices.
And the Qudilex is cold. With very good clean bass as the E1da 9038s. Treble is very very cold/unforgiving, but it does keep the sound layered on its own plane like the Dx220 max.
Astell&Kern ak240 dap sounds a lot like the Dx220 max, nuetral-to-warm without treble harshness. Doesn't layer sound as much. Thus device really has stood the test of time.
Hiby R6 Pro it is generally warm sounding, thick bass and lower mids. And layers music well, but it doesn't give enough attention to the treble as the Dx220 max.