Just got my A90D delivered. It came with Firmware 2.3 already and after connecting it to my Mac Studio with a USB-C to USB-A cable, the firmware drive came up on my desktop immediately. Sound is as good as my A90. Can't really hear any difference with my Sennheiser 660s or with my Sundaras. I have it set it up in High gain and volume at 65 is plenty loud for me. This is really the perfect companion for my Matrix Audio X-SABRE 3
If you updated already you can follow this:
Users can change the gain to
high by pressing the volume knob and turning it clockwise by 2 steps in 1.5 seconds while the knob is pressed.
To change the gain to low, press the volume knob and turning it counterclockwise by 2 steps.
Okay, so granted I am an admitted Topping fanboy, but I am so pleased with this amp!!
My only very minor criticism is that the LED color doesn't really match the rest of the X90 product line. No big deal though...
My main motivation for upgrading was because I had to run the A90 on low gain and with the volume knob way down at like 9 o'clock. There was a little bit of channel imbalance with the volume really low, and the volume was super sensitive.
I was hoping with the A90D I could run it at very low volumes without any channel imbalance. And I figured if I didn't have fine enough control over the volume level, I could adjust the volume on the DAC a touch.
I was pleased to discover that the A90D has extremely fine volume control, even on low gain. And, by virtue of the resistor ladder volume control, the channel balance is always perfect.
I sold my A90 before the A90D arrived so I couldn't do an A/B comparison, but I am so SO pleased with the function and performance of this unit.