Just my 2 cents to clarify :
- Upgraded ST card has nothing to do with the V2.0 printed in the circuit board (I had an V2.0 not upgraded, now back from the upgrade, no visible difference, beside the sound !)
- The numbers xabu is refering to has nothing to do with the OPamp change (it's capacitors !).
If your HM801 has been purchased before Fang decided to change OPamp, then you have the old one, that all... (you can also refer to the QC date tag on the PCB)