I have an Amber 2.2 (early 3) DAC. I've noticed that there is some distortion on louder digital material. I've had three different preamps in my system since getting the Amber, and the distortion has been a constant. Does anyone know if the gain is adjustable (i think it is 3mV in this unit as opposed to the industry standard of 2 mW)? I know the Amber 3 has a gain setting but mine does not. Perhaps a tube change can lower the gain?