I’m trying to replicate the functionality of the Helix expression pedal on the QC, using an expression pedal with a footswitch.
On the Helix (IIRC) the switching function actually changes between Exp 1 and Exp 2, or in other words you end up with ‘2’ pedals in one; if you assign volume to Exp 1, and Wah to Exp 2, they operate as 2 independent functions.
Now I know you can replicate this with things like the QC Mission pedal and the Hotone Ampero 2 Press, but it’s a bit of a workaround; what I mean by this is that the footswitch built in to the pedal operates independently of the pedal itself; all it does is send a latching signal to whatever device (in this case the QC) within which you have to assign the switching.
Now this works fine if you’re trying to use the same combination as in my example above, of a Volume pedal and a Wah pedal - or in other words it works fine with any combination of two devices where one will be on when the other is off and vice versa, because you can assign the Bypass functions of each device to switch on/off when you press the switch built in to the pedal.
The way you connect such a pedal to the QC however is to use the Expression Out in to say QC Exp 1 In, and the Switch Out in to QC Exp 2 In.
So you don’t have 2 pedals plugged in to the QC, you just have the option to turn devices on and off, and use Exp 1 for whatever parameters you want to control.
Where you run in to trouble though is if one of the devices you want to control is something you want to be ‘always on’ - for example the gain on an amp model.
The problem here is a) I don’t want to toggle the amp on an off, so b) if I assign one of the functions of the pedal to be Volume control, and the other to be Amp Gain, BOTH have to be assigned to Exp 1 as Exp 2 is used for the TS cable switch from the pedal and so the amp gain will change every time you change the volume.
An ideal workaround would be to be able to assign the Exp pedal functionality in a Scene - so for example in Scene A I can have the expression pedal control my volume, but in Scene B the pedal will control amp gain.
From what I can see though, I can EITHER have a parameter assigned to a Scene OR assigned to a pedal - I can’t have both; so as soon as amp gain is assigned to a Scene I lose the option to assign an expression pedal to it, and when I assign an expression pedal to it, I lose the option to assign it to a Scene.
Has anyone found a way to make this work?
PS - one workaround would also be to use an Overdrive block instead of trying to control amp gain, as this could be switched on and off in a way that you don’t want to do with an amp. The problem here is that when you’re in volume mode and press down on the pedal to activate the footswitch to turn off the Volume block and turn on the Overdrive block, because the toe of the pedal is down, when you turn on the OD block, it turns on at the max gain you have assigned to the pedal, which is not very subtle. I realise you can use the Invert Range function with the overdrive, to avoid this, but then you have the counter-intuitive experience of being at minimum gain when the toe is down and at max gain when the heel is down 
