The sound I am talking about was first heard on jazz guitar, and I am guessing here, around 500-800 Hz. I can tell you the first thing I heard it on was Russell Malone's guitar on a Diana Krall disc. The sound was smeared and had a "cupped hands" tone. To verify what I was hearing I brought my Polk Monitor 7s into the system and the guitar was crystal clear and articluate. I tried moving the speakers all around the room, thinking I was exciting a room mode, but I could never get rid of it. I heard it on some tracks on the Knopfler disc "Sailing to Philadelphia" too. Just a closed in type of sound. Now some recordings sounded pretty damn good, especially large scale stuff. But once I heard this shortcoming, I couldn't get beyond it.
Oz