So by Bass Lift, that means it decreases the amount of bass, due to the crossfeed having a side-effect of increasing it? If so that is interesting, in comparing to the Headroom amp/dacs with crossfeed; which I think are just the opposite, in that they have a switch that decreases the treble due the their crossfeed's side-effect of increasing the higher frequencies?
I think "Bass Lift" is not a good description of this switch. It covers quite a wide range :)
I have this switch on my StageDAC and I am just guessing it is the same on the Daccord.
On the StageDAC it raises the gain on frequencies below 2khz.
Here is the relevant section of the StageDAC manual: