You mentioned the "Mixing" page - but didn't mention the "Routing" page. I'm not sure at this point if the effect you're trying to squelch is an insertion effect or the master effect. So I'll address both.

Edit - Common/Audio, "Audio In" -> "Routing" (instead of "Mixing") shows a more complete picture of the effects chain for the A/D input. It shows the A/D input has a dedicated set of insertion effects which can be turned on and off, shows the 2-band EQ, and shows the rev/var send (which would be set to zero from what you've said already), and finally shows the output destination (MainL&R, etc).

This isn't the whole picture, however. Switching over to your discussion about variation/reverb: the reverb and variation sends are part of the "system" effects block. So this covers the system effect portion. When the output is MainL&R - everything routed to MainL&R will, at the very end of the effects chain before going out the back ports, will pass through the "Master Effect". Master effect does not have a bypass per part or for the A/D input or anything else which can set MainL&R as a destination.

In order to bypass both the system and master effects, however, you can route the A/D output to the Assign L&R output instead of Main L&R. Anything routed to Assign L&R bypasses the system effects and master effect. During practice, you'd have to hook up and additional audio cable from your keyboard to the mixing board (assuming you use a mixer in the practice location).

(If master effects is the issue ...) The master effect may not be something you care about if you shut it down for all your performances - so you could also turn off, selectively, master effects if this is easier and acceptable vs. using Assign L&R outputs. Easiest way to get there is to touch the "FX" icon at the very top row of your touch screen - which presents 3 effects on/off switches including master effects.

You can play your MP3 files back through the Montage bypassing all of its features and effects.

The A/D Input is designed for routing signal through the various processing opportunities provided by Montage. The A/D Input can be configured on a per Performance basis, it has its own dual Insertion Effects available, its own 2-band EQ post the Insert Effects, you then have the opportunity to route it to its own discreet Output (discreet analog or discreet digital outputs are available) if you choose not to route to these outputs the signal will be available to send to the System Reverb and System Variation Effects via separate Send amount controls; then on to the Master Effect, Master EQ and finally the main L&R Outputs.

The Reverb Send and the Variation Send for the A/D Input Part will default to zero on all Factory Performances. But all Parts using the System routing will pass through the Master Effect and Master EQ (there is no consistent default concerning the Master Effect and Master EQ) ...you can avoid them by routing your A/D Input Part to either the "AsgnL&R" or other USB output options. The Master Effect can be bypassed globally.
Touch "FX" at the very top of the screen
Set the switch for MASTER FX = Off

An alternative method (more in line with what you need) would be to play your MP3 through the Montage using its iOS compatibility- from an iPhone/iPad type playback device connected to the USB "To Host" port - this will allow you to simply play your files through the Montage. Audio arriving this way simply is routed directly to the main L&R Outputs. You'll need a USB-to-Lightning adapter - the volume would be controlled at the source device.

The A/D routing within the Montage is a feature, if all you need to do is send audio to your sound system using the Montage's audio connection to that system, thereby saving audio inputs on that system.... then the iOS method is for you. The other method is for those that want/need customizable and real time control over the A/D Input on a per Performance basis (in other words, its complexity is, by design).

BTW - if you wanted to be a telephone patch-panel operator and get fancy - you could also do something more convoluted:

1) MP3 player to A/D input (one of the two channels)
2) If you already, in practice, only hook up a MONO feed from Main L&R - then you could instead of hooking the Main L (Mono) output to the mixer, you could patch over Main L to the 2nd channel of the A/D input
3) With A/D input as stereo, I'm sure with a mono A/D output - it "mixes"** A/D L+R to a mono feed. So you could have your destination (output) of A/D as Assignable L or Assignable R. Then feed this assignable channel to your mixing board. If the "**" part holds up, then you'll have the MP3 without any system/master effects mixed together with your Main L which does have all of its effects applied because they are "effect"ed before feeding into the A/D input which is cascaded out the assignable port.
** haven't tested if this is true.

The downside is that when you add a buffer stage - you can degrade the sound going through more stages. Haven't hooked all this up to see if it's acceptable.

Lots of options.

USB to host option is interesting too if your MP3 player happens to be iOS. Not having an iOS device - I tend to ignore the iOS integration side of Montage.

Thanks BM and Justin for the suggestions. The assignable outs are a good idea, however I dont have any extra inputs on my digital snake for my mixer so means buying more leads etc. I did however find i still have a camera connection kit lying around for my ipad, and plugged it into the USB host and bingo it works. Only downside it using the camera connection kit disables the volume control. Luckily the Montage has a USB input volume control so Im going to use that for now.

I also found out I can stream wirelessly to my mixer if I buy an airport express as my wifi router using Apple airplay so may go down that route later on.

Thanks again,

Although theres a few limitations with the Montage Im loving the sounds and flexibility of the live controls so far.

Scott

... if you're input limited on the mixer you can use the "convoluted" suggestion which presents only a single cable from your assignable out to the mixer (snake). This uses the mixer inside Montage to merge together Main + Assignable out. It's not an additional connection, it replaces your current connection.

Picture:

imgh.us shutting down - backup:

... if you currently use 2 channels on your snake (Montage in stereo) then you can add to the above the Main R output to the snake as you have now so the two connections would be Main R + Assign L (and that's it) connected to the snake. If you currently route mono to the snake - then the picture as-is works.

Not perfect because MP3 player is a mono connection - but a viable option among the rest.