Hello Funkfish and welcome to the RME User Forum.

In cases where you have a bigger building, multiple rooms, it makes sense to deploy a network-based solution like AVB or Dante to be able to re-use an Ethernet-based LAN infrastructure as well for recording.
But if you have the possibility to deploy optical links between rooms/floors based on multimode fiber easily (or if you have structured cabling as well for optical links) then I still would prefer a MADI-based solution.
Then audio traffic is fully isolated from the rest of the world/network (easiest hassle-free installation/solution).
You avoid potential pitfalls in terms of complexity, add-on costs, potential issues by mixing real-time audio traffic with bulk traffic and what not. No AVB switches needed, no QoS considerations for Dante, no network planning/re-design.

Therefore, would prefer a MADI-based solution to an AVB/Dante-based solution because with MADI, you have a transport medium that is dedicated to the recording solution and which is easy to implement (more kind of “plug & play”).
No potential side effect which could happen in a shared LAN infrastructure where different network payloads are mixed and could impact each other: audio and voice data with real-time demands and other multimedia/bulk data.
Using a shared LAN infrastructure definitively requires more careful planning and might require additional devices. Skills in networking are always a win. Much easier is to implement MADI for audio components, where all this is isolated behind the recording interface from the rest of the world. It's also more robust! (“Oh sorry, I reloaded the router/switch”).

MADI: Optical cabling via multimode cables (OM3 and OM4) is easy to implement and offers you direct galvanic isolation between devices, up to 2 km between devices is possible (option: single mode with up to 10 km between devices).

AVB solutions are layer-2 based and are said to have certain advantages over Dante in terms of time synchronization so that you get accurate audio data even when using multiple devices (similar to the RME MADI extensions -> see delay compensation). AVB is an open standard, so there are no additional costs for a 3rd party chip as with Dante.
However, you need at least an AVB compatible switch when connecting a second AVB device. If you need to cover multiple rooms, you may need multiple AVB switches, or you may have to run longer Ethernet cables. If you are lucky, you have already structured cabling between rooms.

Dante's solutions are based on Layer-3, and it is advisable to implement QoS in the local network. This is not everyone's cup of tea and the components (routers and switches, or L-3 switches) must also support QoS. In my opinion, you require a network engineer or at least a system house for audio installations that is well versed in this and can give you good advice. Network devices may need to be upgraded to support the QoS configuration. Whenever you have a network issue, 3rd party components (switches, routers) are involved, so you require support from many directions, and you require a good network engineer to troubleshoot.

With MADI, you have a proven solution which is fully in the hands of RME which has a lot of experience in this field.

RME offers a wide product portfolio for MADI, AVB and Dante. In the field of recording interfaces, the MADI devices are still ahead in my opinion because they support a colorful mix of different analogue and digital ports and useful features that you can always use. The recording interfaces for AVB and Dante are very “to the point”. AVB, Dante, LAN port (sometimes also MADI port). But that's it.

Back to MADI:
You just have to make sure that a recording interface with 1 MADI port is enough for you. The MADI bus offers 64 channels @single speed. However, if you work with higher sample rates, you will only have 32 channels at double speed and 16 at quad speed.
Assuming that you might want to achieve double speed for higher quality recording, you would be well served with a device that offers a MADI bus for the requirement of 24 analogue ports.

So, you could use a UFX+ as the basis for your recording solution. It offers plenty of ports and connectivity.
— Towards the PC you can connect through USB3 and Thunderbolt (even USB2 is possible, without MADI ports)
— 8x analogue I/O
— 2x ADAT I/O (ADAT2 switchable to SPDIF)
— 1x AES
— 2x MIDI I/O
— 4 Mic inputs (switchable to Line/Instr input)
— 2 headphone outputs which are already superb
— 1x MADI I/O optical (optional via WC connectors BNC)
— word clock
— USB front port for DURec (direct USB recording, backup recordings or use as tape deck in stand-alone mode)
— USB port rear for ARC USB connection
— Can be used in stand-alone mode
— Supports USB Class Compliant mode for audio
— Microphone inputs up to 75dB gain
— AUTOSET feature for Mic/Instr inputs (useful for leveling or preventing clipping)

More information about UFX+

I wrote a blog article about the UFX, contains some useful information, like e.g., a comparison table about the excellent RTL values of the UFX+ and other RME solutions: https://www.tonstudio-forum.de/blog/Entry/68-RME-UFX/

If you need a cost-efficient solution

I would try to get AD/DA converter, that do not need additional patch fields, as additional patch fields are expensive.
For the converter, I would consider the Ferrofish Pulse 16M, which offers 16x Analog I/O through TRS plugs which can be connected through MADI.

How to get 24x analog I/O

RME UFX+ and Ferrofish Pulse 16M give you 8+16 = 24x Analog I/O. As you use the analog inputs for connecting your devices, you have the outputs on the UFX+ still free to connect your active monitors. Therefore, the following device combinations would be sufficient for you (Option 1+2). If you require more I/O, then you can add a 2nd converter through MADI.

Do you need Output of DC voltage (CV/gate) at the analogue outputs?

Consider the new Ferrofish Pulse 16 CV, for this model you need to get the MADI option/module separately.
Check with them whether MADI is also supported for this model, at least the SFP port is still in the back, so I think yes.
https://www.thomann.de/de/ferrofish_pulse16_cv.htm

Check that A/D converter supports different reference levels per port

For your modular devices and synthesizers, you might need consumer and studio level. So, it is an advantage, if your recording interface and external AD/DA converter supports different reference levels which can be set on a per port basis.

This is the case for the UFX+, it supports two reference levels per port: +19 dBu and +13 dBu
Two further well-known reference levels you achieve by raising digital gain (adjustable in the range 0…12 dB):
— set gain to +  9dB to get +4 dBu professional / studio level
— set gain to +12dB to get consumer level -10dBV

For the Pulse 16MX you can also use digital gain to reach a higher sensitivity of the analog port for weaker signals up to consumer level, check the manual: https://www.ferrofish.com/public/downlo … ual_EN.pdf

So, both products give you the needed flexibility in terms of reference level adjustable on a per port basis and up to a sensitivity for weaker consumer level signals, that maybe some synthesizers might require.

Option 1) RME UFX+ and Ferrofish Pulse 16M through MADI, around ~€3959

RME UFX+                  ~€2700
Ferrofish Pulse 16MX ~€1259 (incl. MADI option)

PC/Laptop
|
| (USB3/thunderbolt)
|
UFX+------------+------------- Phones1
|                        \------------ Phones2
| MADI                \----------- 8x analog out for connecting two or more analog monitors
|                          \-----------8x analog I/O for connecting analog devices
+--- Ferrofish Pulse 16M--- 16x analog I/O for connecting analog devices

Option 2) UFX+, Ferrofish through MADI, ADI-2 Pro FS R BE for the monitoring section, around ~€5579

RME UFX+                  ~€2700
Ferrofish Pulse 16MX ~€1259 (incl. MADI option)
ADI-2 Pro FS R BE      ~€1620

PC/Laptop
|
| (USB3/thunderbolt)
|
UFX+------------+---AES/ADAT----ADI-2 Pro FS R BE ---- 4x analog out for Phones1 + 2 or balanced phones
|                        \                                                   ---- 2x analog out for connecting analog monitors
| MADI                \ 
|                          \-----------8x analog I/O for connecting analog devices
+--- Ferrofish Pulse 16M--- 16x analog I/O for connecting analog devices

The advantage of this solution is that you get all the nice features of the ADI-2 Pro for your monitoring section.

RME converters

As an alternative, you could also think about getting RME converters, either M32-Pro or M-1610.
Nice devices with AVB as an option, but here you have to use patch fields with those and this costs on top.

ARC USB

As an option, you can think of adding an ARC USB for more working comfort.

More information

You find on RME product page. But there are also some articles in my blog space that might be useful for you:

You could also think about integrating an ADI-2 Pro FS R BE into the solution:
https://www.tonstudio-forum.de/blog/Ent … our-Setup/

An overview about the ADI-2 DAC/Pro models you can get here:
https://www.tonstudio-forum.de/blog/Ent … ses-EN-DE/

An overview about RME FW/USB/Thunderbolt interface you can get here, it contains a collection from different sources of information (manual, forum, internet, own experience):
https://www.tonstudio-forum.de/blog/Ent … B-MADIfac/
Direct link to Excel file: https://www.tonstudio-forum.de/attachme … 4-08-xlsx/

My setup here: https://www.tonstudio-forum.de/attachme … setup-jpg/
From this blog article: https://www.tonstudio-forum.de/blog/Ent … -DURec-DE/

Please note: I am an end-user like you. All information without guarantee. This information has been compiled to the best of my knowledge and belief. For final confirmation on this subject, please contact the dealer or RME directly.

If you need multiple MADI busses, you can also have a look at these two products:
— MADIface XT (USB3, ext PCIe)
— HDSPe MADI FX

Interface for mobile applications

The Babyface Pro FS is an excellent product for mobile applications. Very portable. An alternative to you could also be the new Fireface UCX II which gives you plenty of features, even mic preamps of the UFX II (flagship interface) with 75 dB gain range and even DURec (Direct USB recording).
I summarized the features here: https://forum.rme-audio.de/viewtopic.php?id=33222

Furthermore, the Digiface USB with its headphones output and 4xADAT/SPDIF capable I/O is small and has good features.

If you need a smaller MADI interface for a 2nd computer, then you can add the PC/Laptop using a MADIface USB.
Yes, you can connect two PCs into a MADI ring of devices then you can read audio from all 64 channels, but of course, you should only write to MADI channels using one PC. I never tested this, but heard that it should work. But remember, every device more into the MADI ring introduces a little delay. For Preamps and Converters, 3 samples at single speed, not sure if this is the same value for a MADIface USB.

Thanks for the flowers Robin, sounds like all is running well, and you are still satisfied :-)

[ Note, it's about this setup: https://forum.rme-audio.de/viewtopic.php?id=30250 ]

You can get a used UFX+, no problem.

Then you already have a few mic channels and also the high quality transparent analogue I/O.
The advantage of analogue ports on such a recording interface, the number of channels is constant no matter which sample rate you are using. Therefore, I like the idea that you might want to get an UFX+.

Connect ADI-2 Pro FS R BE to the AES port, then you still have two ADAT ports free on the UFX+ if you need.

Otherwise, take one of the ADAT ports for connecting the ADI-2 Pro because then you do not need its breakout cable. Not that it hurts, but it's simply less cabling lying around.

Regarding converters, you could also wait a little whether rumours become true about maybe a 16 port AD/DA converter.
Then I would prefer the quality of RME AD/DA converters over Ferrofish products.

IMHO, go MADI .. You have more ports at higher sample rates compared to ADAT.

Another possibility would be to get a HDSPe MADI FX card, I noticed some are available again.
3 MADI buses is "strong" … CPU resource optimizing driver … and you have FX on board (only PCIe card with FX chip).
You can connect the ADI-2 Pro FS via AES port, which is very nice.
There is an optional card to change the 3rd MADI bus to optical … Which gives you galvanic isolation.

But if you prefer standalone operation and a display, DURec … Well, then possibly better UFX+.

As a side note … if you want to record at double speed, then you have only 32 channels left on one MADI bus, with two 16 port or one 32 port AD/DA converter the MADI bus would be full …

If you would like to expand that much, you mentioned a 3rd AD/DA converter or even to take 12Mic …

Then perhaps better HDSPe MADI FX with the 3 MADI buses … you need to count, what you want to connect in the future….