You can use the routing capabilities of total mix in conjunction with room and/or channel eq to setup bass management.

For volume control you can easily make a fader group which includes your main out (left/right) and control it from the main out.
For muting a mute group.

Just solo‘ing individual output channels is not as straightforward as it should be, although there are workarounds for pretty much everything when you use snapshots or workspace quick select.

Not super specifically as things depend on your setup, but as a start (I hope that others also share their experience, or maybe RME even wants to do a tutorial).

You set a high pass on your satellites and a low pass on the sub output channel (Hardware Outputs in Total Mix), using the same crossover frequency.
Then mix all satellite signals which arrive from your DAW in the software playback channels of Total Mix to the Hardware Output of your Subwoofer. You might wanna tweak the levels there and – depending on the gain setting of your Subwoofer – feed it with less than 0dB from the satellites. You also might wanna take into account the LFE convention for theatrical mixing, which sets the LFE channel to +10 dB.

The best cutoff frequency and slope depend on your speaker model / setup / room acoustics. It can also affect how much SPL your system will be able to reproduce in the end, depending on the capabilities of speaker and subwoofer. Checking your satellites frequency response is a good starting point for finding the cutoff, often they sit around 80Hz.
For setting the filter slope see the following topic for some info on how to combine them to achieve 24 db/Oct, as one filter only gives you 12 db/Oct and you might get better results with 24. 18 dB/Oct is not possible afaik.
https://forum.rme-audio.de/viewtopic.php?id=38865

Another limitation is that once you set the low pass on your Sub Output at around 80Hz, that channel won't reproduce frequencies up to 120 Hz anymore. As the filters in Total Mix can only sit on the Hardware Outputs, not on the Software Playback Channels (would be great if that option could be added to Total Mix).
The Dolby Atmos specification probably wants you to have the LFE reproducing up to 120 Hz. This might be neglect-able in practice.
Otherwise: A possible workaround could be to use two Hardware Output channels for integrating the Sub, one for the LFE and a second for its Bass Management purposes which you would connect to the Subwoofer's satellite inputs. You'd then be bound to its internal crossover though and need to match that for the satellite Hi Pass.

Either way, I would recommend something like Room EQ Wizard for subwoofer integration based on measurements.
Start with finding the best position for the sub in the room, then set gains, crossovers and correction EQ against room modes.

I also always cross check with reference tracks which I know really well.

@hselters
Thank you for the detailed reply! The problem that the 80db cutoff will have to reflect on the satellites split to the sub just as the LFE channel was what I was already afraid of as a limitation. It seems, that what you describe would work just as well with RME hardware without the new room-eq with older RME hardware with total mix FX.

Thru a DAW, the bass EQ etc has to be plugin in the DAW.

Yes. If you set speaker delays and eq in the dsp of your loudspeaker, you’ll propably be fine without room eq.

Which subwoofer / speakers are you using?
And do you really need bass management for all?
I am currently getting away with a 5.1 bass managed system through the subwoofers internal crossovers and the rear and top speakers are playing unmanaged down to their roll off.
So far that works for me, the Atmos mixes i did (and heard) usually don’t contain sub frequencies in those anyways.

And what is wrong with the KH 750 DSP?

Exactly! It would rather be good for bass management for as long as I use just two KH 150 as a stereo set. But I will first test with the Adam Sub 10. The thing is that I already know from measurements that the Sub 10 is delayed by about 10 ms which introduces extra latency as you need to align the sub with the satellites. I read somewhere that the Neumann subs are better in that regard.

Interesting! First, I am not exactly sure whether the KH 750 is sufficient for either my room or the system I intend to work towards. My first concern was primarily the inability to do bass management for more than the stereo channels - hence this post! But since the RME interface might be able to fullfull that purpose, it might indeed be an option. However, when utilising the MA 1 software, there might be an advantage in having the bass management not in the sub itself and that is why I am somewhat reluctant to opt for a subwoofer, as long as it is not known what other DSP subwoofer-options we can expect from Neumann.

I agree that the RME Room EQ is probably great for people with older speaker, but it is somewhat behind ... the room correction of modern software like DIRAC or the integrated MA 1 from Neumann does far more the just equalising. It also is about phase correction and this is what makes the monitoring a lot more precise regarding transients and bass.

Wait, I think we are on to something here! Either of us is misunderstanding something about MA 1's capabilities and I hope it is me! So, let me go back a few steps to figure out what happens with bass management and what MA 1 can and can't do there:

For bass manegenemt I am looking for an ideal cut off frequency for each satellite that the speaker is either no longer able to produce with the required volume or in some cases for matters concerning room acoustics where the speaker cannot be placed to a position to produce that lower frequency properly and the subwoofer is. But regardless of the reasoning, bass management means to redirect lower parts of the signal for each satellite to one or more subwoofers. These subwoofers can be exclusively for that type of function or they double as the LFE in a multi-channel system.

With that in mind, let us look what the Neumann DSP line of speakers can do here: there is an important distinction between the AES67-versions and all other version of the KH-DSP line. The AES67 get audio via ethernet cable, all other versions get the audio via analog input or SPDIF. That means, the ethernet port on the non-AES67 versions are not transferring any audio. They are just there for configuration purposes. As soon as you have have done the calibration and uploaded all of the profiles to these speakers, they no longer require the ethernet connection. And that means (unless I understood that wrong) there is no way for any of those to redirect audio coming to the speaker (regardless whether it is analog or digitally via SPDIF) to the subwoofer. With the AES67 variants it could be possible in theory, but it is not. Bass management with the AES67 is possible with the Neumann Audio interface, though, but as I am going to stay with RME, I did not go for the AES67-versions.

If I am not wrong, you mistakenly assumed that MA 1 was doing any bass management, which it does not! In fact, when you you careful read in the description, the word bass management is only used there, because the KH 750 does it and when you use it, you can use MA 1 on two non-DSP monitors like KH 310:

https://www.neumann.com/de-de/produkte/ … ries/ma-1/

I would be a happy man, if what you suggest would be possible right now. But from my understanding, it is only possible to do bass management before the analog or digital connection to the speaker. And that is why the two options I am looking at are either doing it in the RME interface with total mix or routing all analog (or or potentially digital outs) to a DSP powered Neumann Sub that is not released as of yet. Having DSP on the Sub would only help with alignment and room EQ as long as it is not a newly designed Sub that would just receive all speaker inputs and act as kind of a hub for the full monitoring system. But even with such a hub, the ethernet port of a KH 150 still could not receive any audio signal via the ethernet port unless it is the AES67 version.

The thing is, I will have to wait as I don't have the time to quickly set the atmos system up now. I will do a lot of acoustic treatment myself step by step and my current plan is just to set up a stereo working environment with decent acoustics for me to be able to work. From there on I will do a lot of measuring and planing until I feel confident enough to plan out the full system. It also might turn out that an Atmos setup will be too big of a challenge or not worth the effort. In that case I will probably just do another 5.1 system or even quad. But one thins is certain: I am not in a hurry and can wait a bit to see what Neumann or RME come up with. My current concern is only to get the stereo as good as possible and hopefully be able to later re-use everything in the surround setup. And that is why the subwoofer is of concern: the KH 750 is probably good for my current setup, but there might come a better fit for the surround setup. The KH 810 is a bit to expensive for me right now, especially considering that there might be a way more fitting successor coming up ...

The Genelec System surely does look good, but I am already equipped with the Neumanns for now and I will only change that route in case that system does offer anything I cannot ever get with Neumann.

I think you already got it right. From what you describe I see no logical way how this should work.
Where should the signal come from? Each signal for the satellites must be routed to a software or hardware crossover and from there to the sub, no matter if analogue or aes67.
I am sure you also find these answers also in the relevant Neumann manuals.