If the question is can there be a difference between the Parts, the answer is yes. There are Insertion Effects available for two Parts, are they activated for both? Each Part has its own parameter settings that can make a huge difference. Make sure you are not inheriting settings you made. If you cannot figure it out, list the steps you are taking to build your Performance.

It works like this... There are are parameters that are a part of the Voice, and then there are settings that are apart of the channel (like on a mixer) - plugging a new instrument into the channel will inherit the settings of that channel.

The quick fix is to use the Copy function ... Edit > Job > Copy ... see Reference Manual pp. 27-28. This allows you to copy sets of Performance parameters from one place to another, from another Performance or the same Performance. So, for example, if you want to, you can use Copy to make the Main and Layer parts have identical parameters as a starting point, then tweak them separately from there. If you don't use the Copy method, and you merely assign the same patch to both Main and Layer, they're unlikely to have all the same Performance parameters, and to make them the same you'd have to tediously go through them all and adjust them. Copy function avoids that.

Joel,
Regarding the "darker tone" you are noticing on layered parts:

I noticed this too! I couldn't understand why an individual voice would sound completely different when applied to the LAYER PART vs. the MAIN PART.

I suspect you are using a default performance and then changing the voices according to your need. This will change the patch and the default insertion effects associated with that voice, but it WON'T change some of the settings in the PLAY MODE edit menu, which are stored with the performance. The settings associated with the performance you are using are limiting the "punchiness" of the voice applied to the LAYER part.

Select EDIT > PART: LAYER > PLAY MODE

The settings in this menu are responsible for the "darker tone" you are hearing - specifically Gain, and VelDepth (Velocity Depth).

Select the same voice for both MAIN and LAYER parts. Adjust the volume to match. Now compare the Gain and VelDepth settings in EDIT > PART > PLAY MODE by switching between the MAIN and LAYER parts with the PART SELECT button.

For a "quick fix," try creating a performance with the settings you like for quick recall.

Hey Addison,

Wow, good tip. I would not have thought of that. I believe that is going to be the fix. Thanks again,