The QU24 will not do seven stereo mixes, you can switch the two groups to be stereo mixes/auxes. Matrix outputs are not a mix in the sense of creating a mix from individual
input channels, they can create a “mix” of the mixes.
You could create a stereo mix by using two of the mono mixes but building those mixes
would be kind of tricky.
The QU32, QU QPac, and QU SB will do seven stereo mixes as they each have four groups
that can be switched to stereo mixes.