For me, the best use of the SPIDFchannels is locking to my Tascam 2488. That is how I get 24 concurrent channels when I want them. Usually sixteen does it, but not always. When recordings matter I like double mic'ing.

Also, you can loopback any channel, not just SPIDF, but SPIDF are usually unused.

That's the problem when working with beginners.  For the most part, they only know loud, and resist all attempts to turn them down thinking that they sound best at full volume plus one.  In my live gigging days, we played all sorts of rooms.  As a 3 piece band, we did tend to be a bit loud.... but there were a number of clubs where the owners either demanded a lower volume (complete with fines for the band, if levels at the bar exceeded a certain level) to others who simply said.... trust me, you'll sound better in here if you play lower.
 
I saw one band that was so loud, the singer was the only thing in the PA..... and they still couldn't get his vox up to the band's stage level..... (and that was with a 2500w tri-amped PA outside) and the two guitarists were at different places in the song.... one was in the verse and the other was playing the chorus and didn't realize it, even singing the lyrics..... but out front,,,, yeah, we knew.
 
I also played a house gig in a large room.... concrete floor, 20' ceiling of suspended acoustic tile, and bare cinder block walls.  Talk about horrible sound.... we had to play lower in volume until the place filled up a bit and the dance floor was packed. Then, we could turn it up a bit. But it was still a huge echo chamber.  I think they did put up some curtains on the windows at some point in the 2.5 years we played there. It helped..... but not nearly enough.

I was living the nightmare with you as you were describing that evening.

Sorry you had a bad mix experience - lets use it as a learning experience.
 
Feedback:  Feedback is the result of some kind of gain staging buildup Either in the signal chain - or in the air between source and destination.   The real trick to cleaning things up and getting rid of it is having a concrete clear picture of every stage in your signal chain... and keeping it super simple so that in your mind you have a great picture of the balance between air in the room - whats happening onstage - and then the balancing act of microphones, to input gain, eq, compression, and then finally and most importantly POWER.  If your power can only handle so much - like the bose - move that stick right up to the audience and mix that so you can keep your power as minimal as possible.    Did you have a seperate mix for the monitors?  If a singer can't hear themselves onstage - for example - give them an earplug..  because louder is not the answer - and it will only make it much worse and then everyone is miserable.  Guitars and cymbals.  If you are responsible for EVERYONE in the room - not just the band and their uninformed volume war.
 
Speaker placement is key -( I moonlight as both a worship pa guy - and live pa in a few clubs... outside of performing.)
 
I have experience with the bose stuff.
 
On preacher man - That sounds like a fender deville?  Which is a super efficient clean amp that puts out tons and tons of sound that can easily overpower an entire pa... especially the bose stuff.  In many cases those open back fenders absolutely destroy a smaller lower level setup - just pouring muddy lower mids into every available part of the stage.  While the clean side sounds very good, it often forces you to increase the level of the entire venue to match it - which in my experience the bose doesn't really have the oomf to do unless you get a few and place them in key locations.  They just cant move the air to compete.
 
You mentioned that there is a bose speaker behind the band..?  With a condensor mic..?  If thats the case - consider moving that monitor.  As I mentioned - the bose sounds really "Pretty - but with a condensor mic in its field is a certain feedback nightmare.  Its not a good choice for a tight - focused monitor.
 
On the bose stick - in my experience - its best to get that as close to the audience as possible - and I will often - in a band situation - (not a dj style) - flip the bass response switch on the subwoofer to the lowest setting, so that it diverts most of its power to the mids.   It sounds really good but at its nominal setting its very bass heavy - it has a very "pretty" right out of the box sound... which - unless you get a few - gets buried quickly by a loud band.  There is also a pretty nasty 250- 500 hz wall of sound just to the 4 0clock  and 7 oclock part of the pattern.   What that means is that putting the stick next to a wall - is going to send a huge amount of mud along that wall - and back into your stage microphones.

We are going to get together during a practice session to see how we might resolve it.

gswitz
We are going to get together during a practice session to see how we might resolve it.

Oh... is it your band..?  So the setup is always the same?

Nope. I'm just a friend.

That said they have been struggling with this for a while.

And a good friend you are indeed, Geoff.
 
I've done little live recording, mainly because it's a royal PIA, but I've certainly played my share of dreadful rooms!
 
One regular venue I used to play could not have been acoustically worse if they'd tried. It was long and narrow, and the stage was situated, not at the end of the room but in the middle facing the closest wall. To make the room feel bigger, they'd lined most of the walls with mirrors. All we could do was aim the PA in toward the dance floor and play as quietly as was feasible.
 
If club owners (and restaurants and retail spaces) paid more attention to acoustics it would pay off in real dollars. Customers would stay longer, spend more, and be more likely to come back with their friends. They probably wouldn't know why they liked the place, only that it was pleasant.
 

I like being portable. It makes it easy to record in lots of different rooms.
 
It's a nice challenge. I keep my gear stored packed so I don't have to pack it up to go out.

gswitz
I like being portable. It makes it easy to record in lots of different rooms.
 
It's a nice challenge. I keep my gear stored packed so I don't have to pack it up to go out.

Those are all good practices - also - so you dont forget anything.  IF your going to be spending time working abroad you need a "road setup" that stays untainted by your "studio" setup.
 
So here's a few questions as I do very similar work.   What are the exact expectations you are operating under?  Are you selling yourself as a live audio engineer, or as a studio engineer showing up to capture the performance.  Are you expected to mix the room and document the performance?  What kind of console are you using if so.   The mouse controlled daw in a live environment is often not effective in a crisis - such as monstrous feedback.  Ive - for example - had a whole pa screeching while I am flipping through pages on a mackie dl16 ipad in front of a country club.  You need those kill switches that you can hit in a crisis. 
 
If this is going to be an ongoing endeavor where your working in the live domain - capturing - and then returning to remix in the studio domain - etc - you will want to focus first on getting the right live tools.  There are a few digital mixers out there that aren't too expensive that can fire multi tracks to a laptop for later remixing.. yet posess the crisis management needs of a live sound environment.

A good suggestion. I use a DBX compressor as the last stage which has nobs you can quickly twist.

The UCX is compatible for hardware control but I have no interest in it.

Double clicking the faders returns them to zero which is a risk in a live environment.

You can also group faders, which I do. Then, moving one moves three.

Frankly, I'd rather have my UCX than a board. I also have a touch screen which I bring when I'm motivated. That makes adjustments silent.

I don't really sell myself. I have a good day job. I enjoy bouncing tracks. My biggest complaint is that bouncing bands nearly supplants my music playing hobby.

I do often run the sound for the show when I'm there. I make nice recordings for friends usually. I think of it as my contribution to the party. Like the bass player, I bring a talent that adds to the vibe.

I do have a list of things that would be nice to have, but a mixer isn't on the list. A Les Paul is. There are some Mics I'd like to add to the plastic bin I keep Mics in.

I'm guessing that for more than a year, I have never had less that three hours of songs waiting to be mixed. Jazz, bluegrass, folk, rock.

It's my dream to capture a live performance of Noel's band.

http://stabilitynetwork.b.../20160203_Chronyx.html

This is one I'm still working on. I think I have eight or nine tracks to go.