Also, the 4x4 color LCD screen in the studio that has all kinds of bars and charts flowing, is that Pro Tools? How does that work?

Finally, how do professional (rock) musicans challenge themselves? Do they play different musical styles (e.g., a guitarist playing Mozart or other classical string music?)

I read somewhere a comment from Brian May saying he preferred to compose on the piano, since he tends to go back to the same old stuff on guitar.

what is that about? Noise cancelling or what?

Well if you look at it this way, (a) they're playing incredibly loud (b) as they're in the studio, all their instruments are mic'd and running into the mixer. It's generally better to listen to a mix-down of what the whole band is playing through headphones than standing unprotected infront of a 4x12 Mesa Boogie cabinet cranked to 11.

Finally, how do professional (rock) musicans challenge themselves?

Whiskey Actually I find playing different styles useful...even different scales. Oh yeah, messing with the tuning, Sonic Youth style, can do wonders.

i always thought they were listening to themselves on it, or everyone else except themself or something.

Headphones are often used for realtime feedback, somewhat in the same way stage monitors are used. But also for sound isolation. It depends entirely on the engineer(s) and artist(s).

The reason why you wouldn't use a standard stage-ready live PA rig and engineering blueprint for a studio recording session is that it makes it impossible to do multitrack recording. And multitracking has been what studio recording has been about for decades now: post production editing.

That's also why they use sound isolation booths for vocals or other sensitive tasks. Or soundwalls that either reflect, absorb, or diffuse sound within the performance space.

From a recording engineer's perspective, the ideal performance space would have every single artist in a band isolated in soundproof rooms with anechoic foam surfaces available, or even tuned/resonant soundproofed rooms, or other more Machivellian scenarios.

From the performing artist's perspective, that doesn't really work to well, as the isolation makes it a pain in the ass to actually "play" and communicate with each other. So you compromise.

Plus you can play click-tracks for synchronization. Or route specific parts of the drum track to one artist, the bass guitar track to the lead guitar, or whatever makes it work to give the artists the cues they need while maintaining the audio separation the engineer needs.

ahh

Different tunings are great, and I find even just putting a capo on makes enough of a difference to get cool things happening.

Finally, how do professional (rock) musicans challenge themselves?

the recording studio is a musical instrument ... those who want to challenge themselves know this

pity more bands don't do this

mlis, I saw the movie but I don't remember what the LCD screen looked like...it certainly sounds like protools, though. It allows you to do a number of post-production tasks much more easily, because you can work with visual representations of what's going on in each recording track, which are represented as horizontal bars, each with their own seperate controls. Simple things like track volume and balance can be set at any point, and can be programmed to rise or fade at a certain rate (with volume, this is controlled by an extremely intuitive line running across the entire track, allowing you to set it at certain height points that represent the track's relative volume at any point...a sloping line, therefore, makes for a changing volume). Moving tracks to synchronize better with the rest of the mix is possible (usually only feasible with short clips, though). Other slightly more complex things can also be done by opening a new dialog box: levels can be set (that is, the relative loudness of different frequency ranges, from low bass to treble) to make different tracks and aspects of the music stand out at different points. Duration of shorter clips can be edited on the fly. There are tons of other more complex and arcane processes that can be invoked. While digital recording programs like Logic for the mac and Sonar for the PC can be used for mastering, Pro Tools is generally considered the best tool for the job of post-production.

Sorry for the blathering, this is a hobby of mine.

Different tunings are fun, and like Jimbob also said, messing with different scales yields a lot of inspiration, especially the weird ones, like the harmonic minor and its modes.