Crossfeed
Crossfeed indicates whether a headphone amplifier can blend a portion of each stereo channel into the other.
Ordinary headphone playback sends the left channel to the left ear and the right channel to the right ear. Crossfeed reduces this strict separation. It may also shape the transferred signal, rather than simply adding both channels together equally as a mono mix.
Crossfeed — Headphone Amp
The function can make strongly separated stereo recordings feel less sharply divided between the ears. Its effect depends on the recording, the headphones and the implementation, so preference can vary. It is not a guarantee of a spatial presentation or a correction every recording needs.
Check whether the amount is adjustable and whether the control affects all relevant outputs. Compare it at a similar listening level with the function off. Crossfeed is separate from channel balance, which changes the relative left and right levels, and from room simulation or other spatial processing that may add further effects.