"To keep it simple, I have a mixer, an EQ, and a power amp. A mix comes into the board, I control the gain and fader of that channel to ensure adequate headroom, I then have fader controls on the sub-mix, and I have fader control on the main mix. I have input signal control on the EQ and I have input signal control on the power amp. I want to control the volume coming from the speakers. Do I adjust the input signal control on the EQ, or do I adjust the input signal control on the power amp, or do I adjust the fader of the sub-mix, or the fader of the main mix. I do understand the headroom concept of the gain/fader on the board. I'm just not sure where is the best place to control volume from the speakers."The one thing you certainly don't want to do is have widely varied gain settings within that gain structure. You'd never want to have your individual channels wide open while your subs and/or main outputs are barely on. Nominal levels everywhere are generally a good practice. In an ideal world you'd control the overall volume of everything from the last gain stage, in this case the power amp. You could then operate everything else at levels producing the maximum signal to noise ratio (assuming you can determine what that is on the gear you have). Of course, there is another argument that suggests you open everything else up to at least its nominal level (amps all the way up, faders at unity gain, etc.) and control all the volumes with the preamps (gain controls) of the mixer, because those are where most of the noise will come from. I've seen many competent live sound guys literally "mix" using only the gain controls of the mixer.Those two techniques have two things in common: 1) Most of the other gain stages are operated at or near unity gain, and 2) they are both highly inconvenient in most circumstances. There are many variations of those two basic themes, each with its own advantages and disadvantages (see the Tech Tip from 8/7/2000 for one - we have had numerous other Tips on related issues to feel free to search the archives). Here is one of many practical compromise suggestions that are workable and should result in good (enough) sound quality:Set your power amps to levels no greater than what it takes to bring your sound system to the loudest volume it will need to achieve. Any extra gain at the amps beyond that is wasted and becomes noise (not to mention the danger to the speakers [see that 8/7 tip again]). Now you can work backwards though your chain (compressor, EQ, mixer, etc.) to set the levels accordingly. I try to set each device up so I have a limited range of levels I can get to that I think are likely in terms of the upcoming performance. In other words, I will set up the level of the house compressor and/or EQ so I can get nearly as loud as I may need to by driving the board fairly hard (just into the red). Then I back the board off to a reasonable level; one I think I am likely to stay around for most of the evening. We're not talking about huge changes here, but finite windows of likely levels. This admittedly requires a good deal of experience to anticipate, but doing it wrong a few times will clear that up pretty fast. If, over the course of an evening's performance, I discover that I'm reaching the limits of the headroom of the mixer I know I can reach over and get a little more level from the house EQ and/or compressor if I really need it. This sort of "reserve tank" of level functions well because it is something the engineer has to more consciously think about. It's very easy to let a lot of small changes over the course of an evening result in a mix that begins to get too loud. Having to consciously deal with it gives you an opportunity to get things back under control at the mixer, but it's nice to know there's a nearby knob where you can get some more level if you really need it.