You might consider first whether you intend to run any audio through the DN which would allow access to that channel through the DN effects and eliminate at least one mixer destination as it would be summed within the digitone and can be internally panned left and right to follow the DN outputs for an exit strategy.
What is your source on this and what is the potential damage you’re talking about, Is this just conjecture? because it’s not anything I’m familiar with but that doesn’t mean it’s not true.
On hearing it, to me though, this sounds like a fallacy.
The needs of some gear to be split into stereo pairs is different than others, just as an example volcas which use the headphone jack for audio out may not have true stereo but as it is mono divided for headphone output the mono signals are split in an inconvenient way which doesn’t play well with TRS to TRS and requires TRS to dual mono as is the cable you have linked.
I’m not familiar with all the gear you listed but I’d start by making a list of what actually has balanced outputs and can be routed with single TRS cables and what may be using something which requires a splitter or a TS mono cable - Waldorf rocket, for example, has mono VCF input and mono audio out, the headphone out is similar to the split mono of the volca so that it can be distributed left and right. The audio out on the rocket only requires a single TS cable into 1 channel and as along as the mixer has a summing function (yours appears to) then it will split it into the existing L/R channels equally, unless you only want it to appear on right or left in which case you will need to get creative with your cabling because your mixer does not have L/R balance control, only level or stereo/mono options. This is a scenario where one could consider using the DN internal mixer to do L/R pan because the input can be centered, panned evenly left and right, or be panned heavily to one side or the other from the Master page.
Also you may want to do some experimentation with what you actually want in the set up because one noisy device can contaminate the whole thing and rocket tends to be very noisy in my experience however it may not be as bad if your intended power source is multiple power banks, I just don’t know so I can only advise you to figure out which of your devices create how much noise and if you want them to be part of your setup in a worst case scenario.
I don’t know about the audio routing for (audio into) MPC one’s mixer but I assume you can do something similar to DN and unless you are looking for the most basic way to hook this all up, you may have to write down what your goals are sonically and draw up an ideal routing and then make some moves in order to achieve it rather than just assuming there is an optimal single way to do it. I don’t mean that as any criticism, it’s just a box that you don’t need to put yourself in if you want to be objective about the kind of setup you’re after.
One thing to consider is there are some great threads on here where people have already done a lot of mixing of gear in “to go” set ups and you don’t have to take exactly what they do, but just learn from the “abstract”, one such setup is this and he gives some pretty detailed schematics for all his routing so it could at least help you get an idea of how some people are doing things:
I’m sorry if this is not a direct enough answer and just a bigger rabbit hole but it’s unfortunately probably not going to be as simple as A-B-C routing of cables unless some mad genius shows up and proves me incorrect in short order.
I’d start with a piece of paper and an ideal routing, just see if you can use what you have to get there 