The VRM box allowed you to simulate speakers using your headphones, and while I have no idea how accurate or usable the simulations were, they did one thing really well - I really thought the audio was coming from in front of me, like I was listening to speakers. Too many times I panicked when I'd looked at the clock and realized I was mixing after midnight - only to realize.... whew... I was on my headphones. On my vrm box.
With regular headphones, the music usually appears inside of you, somewhere between your ears, with stereo material coming from the left or right. I won't go into the details why this is so, but consider this: When you listen to speakers, both speakers contribute to both ears. Some of the sound enters your ears directly, but lots of it enters later - after bouncing off your table, ceiling, walls.
You get none of that with headphones - the audio goes directly to your ears, one earcup covering each of your squishy input receptacle.
The UHA-4 was bought after much reading to get the same effect of the vrm box with my mp3 player. It has a crossfeed function that bleeds some of the source from one side into the other, simulating what we'd hear with speakers.
Unfortunately, the reason why I haven't touched this piece of kit for years is that the crossfeed doesn't really do much for me. I tested it with logic by panning a mono source to just one ear, and with crossfeed on, there is definitely bleed being sent to the other ear, but I had no change in spatial difference, nothing like the vrm box. It was still inside of me, if a bit warmer. I decided it was time to sell it, so I packaged it up good... and never got around to selling it.
So today I picked it out again to try the crossfeed for shit and giggles, because hey, maybe my hearing has improved with age!!! Yeah riiight. But still I plugged it in and listen to some tunes with my pair of Grados SR80 and I realized something.
This baby makes the bass much "tighter". The bass in the SR80 is normally sufficient but this amp seems to balance out the music really really well. On top of that, the really detailed high frequencies which always make me take off my grados after an hour or so appear to have been tamed and smoothed out. I'm really impressed. All my music is new and fresh again!
