Never had the D2, only two D1s and it does not sound any different to them. Unless you listen via Bluetooth and then you’ll see how poor Bluetooth is on the D3.

I bought the PD3 as it had Bluetooth (I had two PD1’s). I had regular issues with clicks/scratches and dropouts. This happened with two different TWS earbuds. Also I had no problems with bluetooth with my smartphone or my PD1’s/the PD3 (with a Bluetooth transmitter). There has been no firmware...