@Remeniz: In reference to the sound project that we've been talking about, how would suggest I output sound to amp from the Alesis?
The easiest way would be to feed the amp from the main outs using TRS-TRS with balanced cabling or the tape outs using un-balanced phono leads. Balanced cabling is prefered simply becasue any noise/interference thats picked up along the line is usually cancelled out at the receiving unit.
There is 2 ways. 1) I can do Main Outs, however, there is a left and a right channel (does this mean that each is just a TS?)...
The amp accepts un-balanced signals/connections so you can use un-balanced leads with TS plugs.
...and I don't want to run TWO lines. PLUS, I'm going to mixdown to mono anyways before going into the amp because I want the same sound to be output from both speakers...
Ok. But remember that all the mono sources coming into the mixer will be fed to the stereo outputs equally as long as the balance pot is centered. So whether it's guitars, vocals, etc, they will be fed to both outputs equally. You can run just one mono line (left) from the 'Control Room', 'Main Mix Out' or even use one of the Aux Sends from the mixer and split it in two to power the amps channels if you like saving on cable although to be fair i'd run a pair of balanced cables (left and right) to feed the amp if I can.
... so 2) wouldn't it make more sense to use the 2-track tape output (RCA), mix it down to mono to run the line (line will be about 125-150 feet) and then go into the amp?
This is another possibility but remember that the output here is un-balanced and along a long line any noise/interference thats picked up will most of the time be amplified by the amp and heard throught the speakers. Un-balanced runs are great for shot lengths but after that i'm running balanced sets if I can. In my own set up the leads coming from my audio interface to my mixer are only 3 meters long but they are balanced and this is why I get no mains hum pick-up or digital interference even though the cables run close/cross mains cables.
I think option 2 is probably more cost effective if the quality will be the same. I guess, I've got tons of RCA connector laying around, whereas I'd have to buy the TS or TRS connectors.
The only thing thats gonna hinder quality as substandard cabling. Your running long lengths here so use some nice cable, nothing small. Audio cable acts very much like a low-pass filter; the length being the resistance and the capacitance is in between cores and ground and both get worse with length. The worse case sceniro is reduced high Fq response.
Plus, the AMP (GX3) has RCA inputs...
The un-ubalanced RCA's are great for short runs but again if you got the time and cable to do balanced TRS runs from mixer to amp then thats the way to go. If you go the un-balanced route then make sure you keep the audio cables away from mains cabling and if you have to cross mains cable then cross the audio cable at right angles to the mains cabling to reduce pick-up.
Oooh. Forgot to mention, Remeniz. There is an interesting development to this. I guess our church would also like to output sound to a speaker in the basement and one or two in a main floor room, IF POSSIBLE (not a priority). I would need to split the output from the mixer. Would their be quality loss with an RCA splitter? Or would I want to manually split the lines? I would think that I would have to use small powered speakers in the locations listed (you know, similar to studio monitors, I suppose...nothing extravagant and we can't break the bank. They'd need to be like $50 a piece to make this feasible). Can this happen or not really? We don't have much of a budget. Argh.
Active speakers would be much easier and practical to use in the other rooms and an RCA splitter would work fine.
The balanced connections in blue from mixer to amp would be ideal although the green connections are the next best option.