I searched the forum and didn't find a thread to answer specific answers about the M-35. I have a M-35 which I use daily but it still is a bit mysterious sometimes...
Feel free to post your questions/comments in the Analog forum. Typically we add sections as the need arises. So if there is enough message traffic about a particular model or series, we'll add a section for it. Welcome to the Tascam Forums.
If we understand the question as mixers can be very involved as some things hooked up to them can be the problem not the mixer. But let us know what you need as a block diagram can answer a lot about routing issues.