As others have already noted, I have little need for a sound for every spell casted or weapon brandished... to me this just turns it into a PC gamer mentality.
With that said however,
I do utilize a lot of background sound effects.... having a dedicated room to game in helps to do that.
However..... there is nothing like utilizing the surround sound under the table to add background of a loud market place as the PCs search around, or the creeks and drips of a dungeon crawl, or the tranquility of birds in the woodlands as they quest to thru the elven realms. To me this helps my players immerse to full effect.
On special occasions (we call them Game-a-Thons) twice a year, I do prep a special track to use in conjunction with the events..... A nice explosion from out of no where as the evil wizard arrives or a well timed battle music by
Two Steps from Hell, brings the barbarian in the group to life! I have even on occasion, had Gregorian chants in the background when they visit a church or monastery, or howling winds as they went through the frozen north or high seas.....
The trick is that the sound should add, not become the game.. IMO
just my 2cp
DLG