bs2b, done properly
MP95 implements Boris Mikhaylov’s bs2b: a low-passed copy of each channel crosses to the other ear, delayed by the filter itself, while the near channel gets a matching shelf. The centre stays flat within a gentle tilt; there is no hollow around 1 kHz, which is where naïve designs with an extra delay go wrong. The details.
Three presets
Default (700 Hz, 4.5 dB) is the strongest, closest to speakers at ±30°. Chu Moy (700 Hz, 6 dB) is the familiar middle. Jan Meier (650 Hz, 9.5 dB) is the gentlest. Chips under the switch in the Settings panel.
With the rest of the path
Crossfeed sums to unity, so it needs no limiter, and it sits before the output at the file’s rate. It is off by default, part of MP95 Pro on the Mac (free on Android), and the same code runs on iPhone.
Frequently asked questions
Is it the same as the crossfeed in foobar2000 or Roon?
MP95 provides BS2B crossfeed. Other players may offer their own processing or components; compare the documented implementation for the edition you use rather than assuming the settings are identical.