I'm not sure whether I tried using my V2 as a USB DAC, before I disassembled it (and it's not reassembled, yet). But, the Z2 & Z3 will both work as a USB DAC on Windows 10 PCs, using the driver that's provided in the OS - so you don't have to install a driver (which is handy, when you don't have Admin rights to install drivers on a work PC). One issue I have with the Z3, is that every time I get the settings the way I want them - if I use it as a USB DAC, when I unplug it (whether I turn it off first, or not), the settings all revert back to default - which means an Asian language on the display. So, I've memorized which Menu item I have to select, and which sub-Menu item will change the language back to English. On any of these DAP/DAC/Amps - you should be able to reduce the gain of the op-amp circuit, by soldering 10KΩ - 15KΩ 1/4W resistors across pins 1 & 2, and pins 6 & 7 of the op-amp socket. I know this mod works on the Walnut F1 amp (on the op-amp, not the differential line drivers for the Balanced output).