You could use an Equalizer VST Plugins in a VST hosts application like "LiveProfessor".
TotalMix provides then the necessary routing between audio on your system and the VST host.

See this RME video:
https://www.youtube.com/watch?v=qQ95oc6zO3w&t=5s

A very good EQ is Fabfilter Pro Q 3: https://www.fabfilter.com/products/pro- … er-plug-in

I find it a bit unfair to RME to propose a replacement on products from other manufacturers in their own forum.

Especially because stability is one of the core points of TotalMix FX and should not be endangered by 3rd party plugins.

Those who have such special requirements need to have special solutions like an external EQ or see above, which is what I suggested (flexibility, not bound to one manufacturer, more scalability and processing power with nowadays CPUs compared to the not so powerful Shark DSPs):
Then you stand with the purchase of a native plugin that can run on any Windows or Apple computer significantly better than with a UAD solution.

I personally could not consider UAD for the following reasons and therefore would not recommend it:

1. high purchase price, especially also with the UAD VSTs
2. VSTs can only be used on UAD interfaces with Shark DSP, so you are strongly bound to this platform.
3. partly very high DSP resource consumption with the VSTs.
4. quite limited DSP resources for the interfaces, especially for the smaller ones, above that it gets expensive very fast.
5. only the smaller interfaces with few Shark DSPs are available for Windows, but then only for Windows. The better interfaces with higher DSP performance are then also significantly more expensive and are only available for Apple. This is a rather inflexible design. What do I know if I won't switch to Apple because of Window 11. Thank you that I then also have to change my UAD.
6. instabilities under Windows 10 with e.g. UAD-2 Octo card
7. the used Shark DSPs are not very powerful and require quite fast the purchase of DSP resources in form of interfaces and/or accelerator cards
8. quite limited composition of different types of I/O ports, which do not allow flexible extensions via ADAT, MADI.
9. from what I have seen via Youtube I strongly doubt that you can achieve the usual flexibility of TM FX with the UAD Mixer and you will have to say goodbye to other very useful things like DIGIchech or even TotalMix Remote.
10. a bunch of spam in the mailbox. Lots of advertising and bait offers. Some of them are useful, but you can't ignore them completely, because you can't buy them at the regular price, it would be too expensive. Of course, if money is no object...

I don´t think advising other brands is a problem here on the RME forum, but I agree in this case it is not really a good advice, as Ramses stated above, and I doubt the eq is very usable in standalone mode on the uad. BTW I still use and love my 2 uad-1 cards without issues.
I have not tried it, but maybe you can create multiple loopbacks on a babyface. Every loopback will give 3 bands so using the adats for loopback it would not be a problem. You could even obtain 15 bands like that at 44 or 48k.

edit, I had a look on my babyfave and I don`t think it is possible with the loopback function, but not sure, but it should be with an adat cable loopback.

I reread your original post better and what you want is possible. You can split stereo channels into left and right for different settings. If you use adat and not spdif for your loopback you can add 4 roundtrips if needed which will give you 24 bands lol.
Also expect low latency to be better with RME then focusrite drivers.
I would like to add the applying that much correction might not be to good an idea. Speakers should sound just fine as they are and flat and perfect is unobtainable and unnecessary. It is better to get used to the way your speakers sound. All IMHO of course.

Not meaning to piss on anyone's turf but I think we've all browsed through competing brands' products before buying RME gear. RME interfaces sell like hot cakes because they are top quality and very competitively priced, and what I say here doesn't change that. The final choice is always down to features and price. Some times looking through competing products is what encourages to buy RME products, because I am reminded of the features I'll be missing on if I don't buy RME (e.g. Totalmix, Digicheck).

The OP appeared to require a standalone hardware EQ solution to perform some kind of crude room correction. A 3-band EQ is inadequate for that so I mentioned the next best thing that came to mind. That said, I need to make a correction there because I've just checked what actual EQ plugins they offer, and it seems their most flexible EQ plugin is a mere 5-band parametric EQ one that costs 299 USD (now that's value...). Objectively speaking, a 5-band EQ isn't adequate for room correction either (unless the starting room response was already very close to perfect), so my recommendation is not really valid.

The OP may want to try looping audio back through a decent EQ plugin or Sonarworks, as others have suggested, though that's not exactly standalone, or look into dedicated standalone room correction hardware (Dirac, etc) which probably much more.

does the loopback switch switch all 8 adat channels then to loopback ?. when only use 4 channels for EQ (2 for speakers 2 for headphones), can i use the other 4 channels not with a adat able device ?

i hear with headphones or speakers. for headphones i use other correction.i have try in vst but often i forget to switch and after some minutes i think hmm that sound not good. ah forget to switch

automatic speaker correction sound not so good for me. I also develop or change my speakers. diffrent sound is nice when hear ready mixed music. the cpontrol in cubase is only on the expensive cubase version

realy sad that there can not use more EQ. the UAD mixer allow 4 slots and 1 precision Eq have 5 stereo bands.  so 20 EQ possible thats more than enough. but the solo is limit in input and output

As for as I understand it and tried it, you can not use the loopback switch for this. The loopback does not appear on the totalmix inputs, but only at the daw inputs. SO for this kind of loopback you will need a physical connection.
Still I think with more the 3 bands you do more harm then good. 3 bands ok, a little more or less bass. Rmove some mid bloom, add or remove some highs, maybe fine, but more might be a bad idea anyway. It is impossible to overcome limitations in your speakers or room with eq, except for some broad strokes or one or 2 resonances, but better to fix those.

Ah ok now I get it,  I was already thinking I only ever needed that kind of eq in a live situation.
There is one other solution for the loopback I guess, you could do an analogue loopback of outputs 3/4 to inputs 3/4 and gain 2X 3eq's (and loose the headphones out). That way you adats are free. With this quality of converters that is no problem. Cause the babyface has snapshots you could also use both methods in different situations when needed.
I like your way of thinking in getting the most out of this device.

There's no connection between the interface's buffer size and plugin latency. A plugin can process each sample in the stream in real-time with a latency of < 1 sample from input to output - the limit is the CPU performance, not the sample rate. A plugin will process an incoming sample as fast as possible, send it down the chain, then idle till the next sample arrives. The only time it necessarily takes longer than 1 sample is if you're running a convolution or function that requires multiple samples as input - now the limit is the sample rate. The latency is the number of samples required by the function and is not related to the interface's buffer size. The plugin typically operates on pre-existing input and output buffers. Each time the plugin is invoked, it's informed how many new samples are in the buffer. All of these new samples can be simultaneously processed in < 1 sample latency depending on CPU performance. It doesn't need its own IO buffers which would add latency.

Changing the frequency response with EQ requires phase shifts and necessarily adds output latency in the order of a few milliseconds.

Equalizer APO supports hosting VSTs. You can see the latency and CPU usage of all the stages you've added in Equalizer APO.