From memory can you elaborate a little bit on the difference between the A90 and A90 D ?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.
I never heard the original A90 but my impression of the A90 D is that it is a very natural neutral with a touch of warmth.