Yeah, I know, all the old farts over 50 say FILL IN THE BLANK isn't the same anymore. The problem is if they are referring to live music performances they're mostly right. Nowadays, unless you're going to a house concert or a classical music venue, chances are you won't hear anything "live" as in acoustic instruments in a natural environment - any and all instruments at a live concert will be sound reinforced.
Sound reinforcement gear comes at many quality levels from the 30-year-old Peavey active boards held together with gaffer tape hooked up to wedges that look as if they've been used for ordnance practice, to state-of-the-art rigs that cost more than even Vlad the Impaler Putin's home stereo rig. And there's everything in-between.
Just like most music lovers I've heard more bad sound reinforcement than good, but sometimes the good can come from modest amounts of gear. Old Blue Sound Company, who do the Mid-Winter Bluegrass festival in Northglenn, CO, have year in and year out with many different equipment combinations, delivered more than merely adequate sound for that fest. I usually try to sit close to their board, near the back of the hall, because their sound is nicely balanced and not too loud.
Some other local venues here in Colorado have consistently execrable sound. I won't name names, but one particularly popular venue, with a great reputation in the bluegrass community has never, ever, sounded decent. Even when I've played there, after a careful sound-check, by the third song the volume had creeped up and turned to mush. At this point I wouldn't bother to see God there if he sent me tickets to front-row seats on a golden calf invite.
And what, besides having decent gear, separates the good live sound from bad? The ability of the sound engineers to hear and how much they care about what they hear. In a recent article in Mix Magazine May issue (which if you don't subscribe to I recommend for no other reason than to see how the mega-buck techs do their thing) they had an article on Ellie Goulding's tour set-up. Except for a very unfortunate pic of Ms. Goulding wearing what appears to be leather, bondage-inspired hotpants, the article was excellent. Among the gear used were not one but two Bricasti M7 reverb units at $3700 each. And instead of one or two harried techs, the Goulding tour has at least five (with several assistants as well) and all of them are seasoned pros. Perhaps the sound still sucks, but I doubt it.
Of course some venues and the locations within those venues will sound better than others despite a sound technician's best efforts. If you go to this link you'll find ten videos of the Infamous Stringdusters' live shows. Compare the first vid, which sounds pretty awful, with the second vid, where the sound is quite acceptable, with the third, which is even worse than the first, and you can hear the primary problem faced by sound engineers - the sound is different depending on where you are in the hall, and it's virtually impossible to make the sound equally decent throughout a hall.
What's the takeaway from this? I recommend finding a venue that you like and spending some time figuring out where the best-sounding seats are located. Then, try to get as close to that location as possible when you go to hear live music at that venue. That's what I do. Sometimes you win and other times, well, there's always earplugs...