I really think it's a combination of many things, except gear. You could argue that it is the fingers, but I think it's more of the entire body as a whole. Like the guy Hack mentioned above. I've seen deaf people standing directly in front of PA bins, and absolutely grooving to what vibrations are coming out of the speakers. I always thought music to be a true connection to the Force, and how certain frequencies can affect one's behavior (for better, or worse). A good example of this is the different oscillators, noise generators, and synthesisers that were used by Hawkwind's Michael "DikMik" Davies. He was quoted as saying he had the power to turn the show into a wild mind blowing experience, or turn everyone physically ill (which had both intentionally and unintentionally happened). Another good example is you would not see people wanting to slam dance during a performance of Yes's "Close to the Edge", but you would to The Damned's "Smash It Up." Just like people would dance uninhibitedly to Little Richard singing "Tuttie Fruitie", but not to Handel's "Water Music." It would be far more restrained, if at all.
Music's frequencies flow through all life forms on this planet. There have been tests performed that show plants respond to certain types of music over others. The same with pets, and other animals. Music does tame the savage beast, or sets him off violently.
As a result, I think it's all in one's internal wiring. The ears, central nervous system, skin (it is an organ), fingers, et al. It's how all of your senses respond to the sound waves, and their manipulation. Even the eyes are an important factor as many people see notes as certain colors. Hendrix was one of those people who you could ask "could you play that a little more red?"
As a result, I argue against gear. Unless it is just good versus utter crap. It doesn't matter which guitar/amp combination, or pedals I use to get "my sound", or a sound I'm pleased with. That includes a mix of Gibson, Gretsch, Fender, and Rickenbacker guitars, and Marshall, Ampeg, Hiwatt, Vox, Fender, and DST amplifiers. I can dial in a sound real quick, and don't need to bring an amp I plan on performing with on Saturday, to the previous week's rehearsal. Other than making sure it works before it leaves the cellar, I know I will dial in a good sound in a couple of minutes. I've also used backlines before, and I was able to get a sound I was relatively happy with pretty quickly. Gear is all personal preference and to what ends it needs to be used. I hope that I still have one or two more records in me, and live performances for a few more years. After that, there may be a drastic switch in what I decide to hang on to for just playing around the house. Will I still keep a full stack around so I can feel my pants being blown by the air coming out of 8 - 12 inch speakers? Yeah, probably. But I may find the amp I chose to play while at home may be something more like a Vibrolux. Who knows? It will be whatever my central nervous system tells me still sounds pleasing to my senses.