what crossfeed is? is it something to remove gaps between tracks? if so, it doesn't work for me

Crossfeed mixes left and right channel to reduce stereo separation.
Good for headphones. They won't blow your head anymore.

Not to be confused with crossfade.

mind explaining why you think this is good? I'm having trouble understanding why you'd want to intentionally ruin the stereo image, and especially what you meant by "they won't blow your head anymore."

Doh!

No wonder it didn't sound like it was doing anything.

When done properly, crossfeeding does not destroy the stereo image. Simply put, headphones do not provide natural imaging. Listen to music with hard-panned instruments and you'll immediately hear this. Such "one ear only" sounds rarely occur in nature.

Hard-panned instruments are an extreme example, but the same is true for all stereo recordings. The brain uses both ears to localize sounds and when listening with headphones, the brain's primary localization cues are lost. The brain constantly fights to figure out where the sounds are coming from. After about two hours, the brain gives up--listening fatigue sets in.

Crossfeeders attempt to fix this. Some use ambience recovery, others use delay and other head-related transfer functions (HTRF). My crossfeeder (available as a DSP plugin for Winamp and built into Foobar 2000) is of the latter type. Give it a try, you might be surprised.

now that makes a bit more sense. from reading the other post I assumed it was just mixing the two channels to something closer to mono. thanks.

In it's very basic sense that is indeed what happens, but with some degree of delay between the channels (in good old electronics this is just accomplished by an RC arrangement). The end result is instead of the stereo image being positioned inside your head, it's moved forwards into the right position.

What exactly is ambience recovery? Is it a modeling of "early reflections," meaning a series of delayed images of the original audio designed to mimic echos off the walls of the room? Is it an "audio snapshot" of the reverb in a room, applied continuously to the audio signal to emulate a room's reverb and tonal characteristics? Or is it something totally different?

I'm using Winamp2 with the DirectX plugin manager, running TrueVerb (which is a combination multi-tap delay and reverb, designed to mimic room reflections) piped into your crossfeed plugin. The result is a wonderfully open, slightly "live" sound that removes the stuffiness of center-panned music.

You pretty much hit the nail on the head. It can be done many different ways, but the result is always the same: simulate a room's ambience characteristics. I've experimented with some known ambience recovery methods, but thus far the results haven't been that great in my opinion. I was thinking about trying to mix them into the current crossfeed (kind of like what you did with the reverb) to get the best of both worlds. Future versions might have some cool new toys!

well, I understand a bit of HRTF stuff so I can understand the concept now, the small amount of delay can do quite a lot in terms of avoiding the mono effect. Did a bit of HRTF research after being quite impressed with what I heard with my Aureal vortex2 card and good A3D 2.0 coding in a few select games.

What programs have you used? I tweaked TrueVerb around until, in a fair amount of songs, I can't immediately tell if it's on or off. I'd say it's as subtle as your crossfeed plugin: sometimes it's an obvious benefit, sometimes it isn't so obvious. With these settings, TrueVerb isn't adding reverb so much as it's adding some "openness" (all of its default settings totally alter the mix). With some adjustments, I think this would really add a new dimension (no pun intended!) to your crossfeed plugin. I've found myself listening to music for much longer periods of time after adding TrueVerb to the Winamp output, but that might just be a coincidence.

Then again, I didn't mind the 40%-mix preset of your old crossfeed plugins, so maybe my definition of "acceptable alteration" of the sound, in the name of better spatial orientation for headphone use, might be more liberal that others' definitions.

P.S. Trelane, I sent you a PM.

And what exactly is your crossfeed plugin called? "Trelane's Crossfeed"? You should come up with a cool name, like "Headache Eliminator Pro" or something. B)