Hi Daniel. This is the Sabre 9018 DAC (model uae23hd) correct?
Gain can be reduced by replacing R19, R20, R21 and R22 with smaller value resistors. 780 ohm is used now, you could try something like 470 ohm.
The USB receiver in both DACs are called SA9023, so if you use Linux it will often call it 9023, even though it's the Sabre 9018 DAC. The Sabre 9018 has a red LED on the top, while the ES9023 DAC has a green LED. So please check this first.
Yes, the USB chips are called SA9023, very similar to the ES9023 chip used in the other DAC.