Hello!
Can I program the MC8 to control 2 different parameters in an effect pedal using an expression pedal? Say I’d want to turn the Effect Level up and down while simultaneously turning the Direct Level (dry level) up and down?
And if so, could I turn down the Effect Level when I’m turning up the Direct Level? In other words - could the two parameters go in opposite directions?
Yes, you can do that. Just add 2 Expression CC messages to your Expression Pedal preset and swap the max and min value limits for one of the messages. That way one will go up and the other down.
That’s awesome. That would mean I could have a perfect mix when the expression pedal is set right in the middle. I could then easily tip the mix either way. Using an ML10X with an MC8 and an expression pedal makes a line mixer completely pointless. As long as the pedals in the loops are digital and are capable of setting both the dry and wet levels.
The only question then is - are there any expression pedal out there with a screen showing the setting between 0% to 100%? That would be very helpful when setting the level.
The MC8 actually shows the expression pedal percentage on its screen which I think is enough, at least for my use cases:
There might be some expression pedals with a screen out there, but those are probably way more expensive.
An expression pedal is basically just a knob, so adding circuitry and even a microcontroller just read out the value and display it is a bit overkill. But some company out there probably makes one.
Oh. And if the screen is on the expression pedal you can’t read what it says with your foot on it anyway…
So, in other words, I can basically use any expression pedal I want and the MC8 will display its position (heel/toe) in percentage?
If so I’ll definitely treat myself to a Lehle 
Programming MIDI is new to me so I’m wondering if I could program the MC8 to have the expression pedal control several pedals at once? I plan to have all three Boss 500-series effect pedals hooked up to the FX-Loops of the ML10X (MD-500, RV-500, DD-500).
All three are routed in parallel to each other.
• So let’s say I program the entire sweep of my expression pedal to go from 100% wet (toe) to 100% dry (heel) for the Boss DD-500, so right in the middle of the sweep there’s a point where it’s 50/50 wet/dry.
• Then perhaps I simultaneously want the Boss RV-500 to follow the same pattern but since I already have the dry signal through the DD-500 I assume I could simply set the RV-500 to Kill-Dry and have the expression pedal only control the Effect Level to go from 100% effect (toe) to 0% effect (heel)?
• Then perhaps I want to include the MD-500 into the sweep as well but have it to go from 100% effect (toe) to 20% effect (heel). So when the effects from both the DD-500 and the RV-500 are completely silent I have a mix of dry signal and 20% effect from the MD-500 still coming through.
All in the same sweep on the expression pedal. Would that be possible?
Sure, that is possible. You’ll have to think through if you want to work with fixed combinations of control parameters or if you want to programm each parameter to a seperat patch. Both would be possible.
But I’m not sure if it is possible to control the dry volume via CC on the RC. I know for sure that the track levels can be controlled individually but if I remember correctly there is no way to control the dry level or the overall output.
Nevermind you’ve been talking about the RV not the RC 
Just to make sure I understand you correctly.
With “fixed combinations of control parameters” and " or program each parameter to a separate patch" you’re talking about the programs/patches on the switcher? Meaning, the programmed combinations of effects on the ML10X? So that the same function of the expression pedal in the MC8 does the exact same thing on every program on the ML10X? I might have the wrong understanding of the word “patch” 
No, I meant that you can either have for example dd dry lvl and md dry lvl programmed to a single button on your mc or have them on seperat buttons, which would allow you to choose various combinations.
Just check it meets these requirements:
The MC8 works only with TRS expression pedals. Expression pedals fitted with 10k ohm linear potentiometers give the most accurate and smoothest response, though 10k - 25k ohm linear potentiometers will work too. The potentiometer wiper should be connected to the Tip of the stereo cable, while the Ring and Sleeve should be connected to the outer lugs on the potentiometer.
The Lehle expression pedal is a dual expression pedal and according to the specs:
“Both outputs can be used with almost all common devices with expression inputs from 5k to 100k , including TS, TRS and/or RTS. The 10k output can be set as a latching- or momentary switch. Resistance value of the potentiometer: 5-100 kOhm”.
Also, it has a USB as well and:
“via the USB jack you can send MIDI data to a computer for the control of MIDI-compatible software”.
So perhaps this is a better way of connecting it to the MC8?
No, the MC 8 doesn’t provide usb host functionality (MC 6 Pro does), You can’t hook it up via usb. And there have been some posts on the forum which indicate that the Lehle dual doesn’t work properly with the MC. Expression pedals compatible with Morningstar? - #57 by mr_pediri
