The dual AK44893 DAC chips on the original M11 have been upgraded to dual AK4497EQ DACs. The upgrade promises improved signal to noise ratio and reduced distortion.
FiiO has also boosted its battery capacity from 3800mAh to 4370mAh. Not sure what this means in terms of usage time. But the original M11 offers about 13 hours through the 3.5mm connection and about 9 hours using a balanced connection. So, expect more than that. And standby time has been improved from 50 days to 60 days.
You can look forward to more internal storage capacity as well. The M11 Pro now gives you 64GB of ROM versus the 32GB offered by the original M11.
FiiO has employed the THX-AAA amplifier chipset, which is an improvement from the original M11’s OPA926*2. Nanu-nanu.