It all begins with stage volume
I get it -- you wanna hear and feel your performance on stage. As someone who plays both guitar and bass, I really feel you. And to get that thump on guitar or bass you need to turn it up the amp, right?
Well, someone needs to crank the volume, but that person is not necessarily you.
What we're going to explore is the additive nature of sound...
But first - you need balance, Daniel-san.
The key to getting a great live mix is ensuring that the sound sources on stage [amps, drums, bass, etc] all have a solid, balanced mix without any help from the PA.
Then we can add-in the kick and snare mics enough to fill out the drum sound a bit. (I always try to mic the toms as well, but it's not always possible.) From there just enough vocals need be added to the PA to have a balanced complete stage mix with the vocal sitting on top.
Once we have this, we have our stage volume. Then the FOH person can raise the levels at the same ratio as your stage volume and get a great base mix to start really building out a slamming house mix.
Its worth noting that the lower your stage volume is, the easier it is for stage monitors to give singers a great level without feeding back. And once you have that balanced out, your FOH mixer can use the PA and subs to rock the venue. If the venue's PA system has been designed, assembled, and calibrated properly for the space, you will really feel it even though you're not cranking your amp.
But for all of this to work - the amps and the drums (at the very least kick and snare) need to be mic'ed, and the bass player absolutely needs to provide a DI from their amp into the board.
But, what if your rig only sounds good cranked up, what do you do then?
Well an amp shield is a start. Confine that sound, so when it's turned up, it doesn't blast straight out and "beam" the persons standing directly in front of it, or rise above the house mix. Shielding your amp will lower the perceived stage volume, while allowing the tubes to run wide open and get the speakers moving.
Musicians tend to suffer from the fact that they can't be in two places at once, and therefore can't hear what it sounds like out in the house while they're playing. If they could, they'd immediately interface with their FOH mixer and ask, "What do you need us to do to make all if this sound great for our audience?" And if your sound guy/girl is worth their salt, they'll tell you where you need to set your volume. Then the trick is for them to get you from that initial balanced stage volume up to a rockin' stage volume that is the accumulation of both the house mix swelling back onto the stage, and the monitor mix. That's when things really thump.
And now we've come full circle and are ready to talk about additive sound
That rockin' stage mix I just mentioned, comes from sound being additive in nature. This is often missed by both musicians and sound mixers alike. It's a culmination of all the amps, drums, monitors, and the wash from the PA.
The other thing that is often missed is the max amount of sound a room can handle before the frequencies all start smashing into one another.
If you're mix is right on the edge of maxing out your room, and you turn up the vocals in the mains without lowering it an equivalent amount in the monitors - you're gonna get some feedback.
If for instance you're at a gig and ask for more vocals in the monitor and it feeds back. The mixer will likely bring that vocal volume in the monitors back down. If the talent persists on more vocals, the mixer has no choice but to lower the vocal level in the house. If that move buries the vocal, then your initial stage volume was too loud and imbalanced for the space and the gear being used. I see this all the time with the bands that play before us and the one's after. And it's simply because their amps are turned up too high.
We used to have this problem as well, and then I built the amp shields and we spent an entire rehearsal dialing in our stage volume, then resetting everything and doing it again until we all know where to set the amp volume, and when it feels perfect.
To see this additive phenomenon for yourself. Do an experiment with your own PA.
I did this for my own band, so they could better understand the concept. We have 3 stage monitors because 3 of us sing. So I piped some music through one monitor at a low volume. It seemed pretty weak, no thump - no feel. I muted the feed to that monitor, and sent the music to another one - by itself. Again the sound was weak. Muted it and did the same thing to the third monitor to prove that all 3 were at the same approximate volume individually. And then without changing the levels, I un-muted the other two with about a 2 second pause in between each so they could hear the volume and fullness jump up as each wedge was added. And their eyes grew wide as things got instantly warmer and fuller and you could feel a little thickness.
Then I muted all three monitors again and put the music through the PA pointed away from the band at a medium volume... it was pretty weak on our end. So I then turned on just one monitor and suddenly there was a little bit of fullness, and then then un-muted the other two and finally we could feel the music thump. If we had a sub in our PA, the ground would have shook. Individually, none of the wedges or the 2 main's could deliver a thumping mix, nor were they turned up very loud. But cumulatively they were slamming.
So work to understand additive sound, and when you get to the gig, work with your sound mixer. You won't always get someone who really knows what they're doing, so it's up to you. Do your best to craft a well balanced stage volume on your own in your own space. Get to really know your sound well enough to adapt it to every space you play. Doing so gives you a much better chance of having great sound. And when you do wind up with a competent mixer, you'll have a pretty good chance of having a fantastic sounding show. And when you get a great one, you'll shake the building and your crowd.