I've been getting a real education watching sound engineers go to work at venues.
They always walk into a venue and first thing they do is clap their hands. I asked why and found out they're listening for how "long" the space is. In other words they are listening for how long the natural reverb is and what the predominant direction is. This is how they dial in the reverb for the venue.
Then sometimes you hear a hissing/water noise being played through the sound system. Again I ask - this is "pink noise" and with it playing they run around the venue using analyzer mics to find out what frequencies to boost or drop depending on the acoustics of the venue, the weather, etc.
Then before sound check they pump Steely Dan's Aja through the system and listen. Why? I was told that recording is so alive and near prefect that it is what the trained ears use for a final check. Especially the drum track. If you have all the ranges covered and can hear the stick click mistake in Gadd's first drum solo clearly then the sound is dialed.
I'm in awe of how great sound people who really know what they're doing can make a band sound. Me, being the mischievous lead player (aside: I was told last weekend the difference between a lead guitar player and a terrorist is that you can negotiate with a terrorist) I am I showed up at an outdoor venue with a Pro Jr. Had my rig in truck but just decided to see what sound would say. I presented the little amp and said I wanted to use it for the show. Fully expecting to get a reaction all that happened was sound said "Okay" proceeded to put the mics on it and fed it into my monitor. Guess what? They made it sound great and actually told me how much they loved the sound. Go figure.
The other thing that amazed me is how they get the band to sound consistently good in all types of venues. Whether blasting outdoors or at a smallish club it aways sounds pretty much the same.
And great sound, man-o-man, does it ever open your playing up! You don't have to fight for space and you can let the notes bloom and finesse them. It has taken my enjoyment of performing to a new level. I've come the conclusion that while pro sound is expensive, it's worth every penny.
Chuck