The Anniversaries mid-range is thicker, fuller, and more intimate - the mids on the X1 can sometimes be a bit distant sounding in comparison. While I normally don't strive for an intimate sound, I can hear the appeal it can have - sometimes when listening to music on the X1s I want to turn the volume up louder to bring back some of that intimacy. On the other hand, sometimes I don't want that intimacy, and during these times I prefer the X1s approach more. Some examples are gaming, movies, and TV - all areas where I tend to prefer a more distant presentation. The way the X1 presents its mids seems to allow it to free up a little more space and room inside the soundstage, which seems to benefit all the just-mentioned examples. If you are specifically looking for an intimate mid-centric headphone, you may want to think twice about getting the X1. You should probably look into the HD650 or Anniversaries instead. beats solo hd There are plenty of mid-rich as well as mid-recessed headphone options out there, but there is a fine line in the middle of the two and I think the X1 falls more closely into this area.
For me, this is a VERY important aspect of sound. In fact, it was pretty much THE determining factor on whether or not I would keep the X1s - I'm absolutely a soundstage whore, and I could care less about the rest of the X1s sound signature if it did it all with a small and claustrophobic soundstage. Luckily the X1s soundstage and imaging were a pleasant surprise. Both were better than I was expecting and they sealed the deal for me.