What DC offset do you measure on the headphone jacks? I measured yesterday on the G, R, and L labeled contacts on the headphone jack board using Fluke 87 V DMM. The unit was idle for ~10 min before measuring. The values are
G & R: 2.1mVDC
G & L: 6.8mVDC
The offset on the left channel is higher then 5mVDC I would be comforable with. The values shouldbe as close to zero as possible, as the voltage causes the headphone coil to be shifted in 'neural' position affecting reproduction.
The unit I have has slighly higher volume in right channel. The difference is annoying. I tested the same source with AMB M3, and M3 plays both R and L channels with the same volume even after swapping RCA cables. Reached out to Kingwa for resolution. Let's see what happens.