I can confirm the interference is much worst that with 3G version.
Anyway, can be solved by using airplane mode:)
Issue also mentioned in this test:
But I can feel what is improved: more Transparency, Dynamics, Resolution, Detail...with slight (little) additional Bass.
I also notice sometimes the imbalance, but not above my tolerance.
I wonder how this can beimproved on Portaphile 627.
But for me too much on negative side:
for me at least twice higher the price: 549USD ~ 420EUR (+27% import tax!), vs 250EUR for the Arrow 4G (but was 210 EUR for me as refurbished 3G ungraded),
Very whort battery life, no USB charging, no auto power on/off...but anything like bass/treble/cross no need for me.