Tread carefully here. Tried it and, long story short, the bit perfect volume does not appear to work on Linux. At least, I was unable to get it to work - after input from some luminaries and DIYINHK itself - who essentially said they had not tried it on the Linux platform.
Ended up going the Hifiduino route for volume control digitally. And there was an issue there as well - if you use the modified firmware DIYINHK XMOS board then there is an I2C conflict which leads to horrible jumps in volume when the sample rate changes. With much helpful investigation and advice from BlgGear at Hifiduino the solution appears to be to buy the K2M and the non-modified USB board (either the standard one or the isolated version) and implement the very elegant Hifiduino solution which allows remote volume control with the aluminum Apple remote, ESS 32-bit digital volume control, LCD display and the ability to manipulate all the digital filters in the K2M.
I used an Adafruit Pro Trinket 3V (so did not need logic level converters) and one of Adafruit’s quarter size perma proto boards - everything fit neatly, including the two pots for contrast and backlight brightness, with a little cutting of traces. Mods to Hifiduino’s code were straightforward - mainly to accommodate the lack of pins 2 and 7 on the Pro Trinket. And yes, it sounds great!