I would start with a combination of UFX III and ADI-2 Pro FS R BE or ADI-2/4 Pro SE.
The UFX III gives you a good mix of different port types, MADI, and two already well headphone outputs.

The ADI-2 series of interfaces give you excellent features for monitoring and two headphone outputs as well.

I would recommend isolating the UFX III behind a USB3 PCIe card with a supported chipset. Then you are more independent, adding USB peripherals as you like without impacting the UFX III.
The Sonnet card with USB Type A ports and FL1100 chipset is known to work well and has driver support in Win10/11. I wouldn't be frightened basing the system on USB, with RME drivers it offers a great performance comparable to PCIe.

If you run out of ports you can connect further devices using MADI.

Some blog articles that I wrote some time ago which cover these topics:

The new UFX III and some pictures, also a diagram of my setup:
https://www.tonstudio-forum.de/blog/ent … iii-en-de/

Differences and features of ADI-2 Pro DAC/Pro FS (except the new ADI-2/4 Pro SE).
Good to get an entry about the advantages of these devices:
https://www.tonstudio-forum.de/blog/Ent … ses-EN-DE/

How to integrate the ADI-2 Pro series devices into your setup:
https://www.tonstudio-forum.de/blog/Ent … our-Setup/

An excel sheet comparing the different RME USB/FW/TB interfaces:
https://forum.rme-audio.de/viewtopic.php?id=35156

A large "artificial" Cubase project as performance benchmark. 400 tracks / 803 VSTs.
Runs without audio drops at the lowest ASIO buffersize at single and double speed on my system,
which is basically from 2014, with a few upgrades... Same good performance as RayDAT PCIe card.
https://www.tonstudio-forum.de/blog/Ent … cks-de-en/

RTL comparison of different RME solutions that I owned / tested:
https://www.tonstudio-forum.de/blog/ent … cts-en-de/

My current setup:

UFX III also used as parallel effect loop for stereo setup of combo amps and two  Lexicon PCM as external FX 100.
Lexicons can be used for a) Marshalls, b) Cubase, c) PCM81 for Marshall and PCM91 for Cubase  (simply by different routings).
FC-300 for FX selection, tap tempo, etc ... and a MIDI splitter to distribute the Tap Tempo via MIDI to the two PCM's ..

The rack with Thomann Eco rack, 23 cm depth, the Lexicons need more.
As I have no active cooling 1 RU more to have some space between devices for better airflow.

Amps recorded with 2x2 Mics, in most cases standalone with DURec, using UFX III as tape deck.
Reamping possible, because I plug guitars in the very good Instrument (Hi-Z) inputs of UFX III.
Rack tuner on top of left amp .. had one analog port free on the UFX III, so I can see / check tuning at any time.

If you need more flexibility in placement of the UFX III and other components ..
I am using two Startech active USB3 extender which work fine.
Then you can have even longer cables than 3m in total, two of such extenders can be cascaded.

Setup for you could be e.g.:

PC---USB---ARC USB
|
| USB3
|
UFX III-----------AES or ADAT or SPDIF--------------ADI-2 Pro FS R BE----- monitors
          \------ 2 headphone outputs                                               \--------  1-2 headphones

The ADI-2 Pro has a SRC (sample rate converter) built-in which can be useful to add devices with fix sample rate

If you want to record / digitize Vinyl, then consider getting the ADI-2/4 Pro SE.

For the inputs :
https://www.rme-audio.de/12mic.html
and for outputs :
https://www.rme-audio.de/m-32-m-16-da.html

Are you aware that the onboard DSP is a closed system, not for VST plugins ?
Sometimes people think DSP means it can load VST plugins and VST instruments...

You can use a Mic Preamp as A/D converter, but it would be better to get an A/D converter supporting different reference levels.
Also for operational reasons, the Mic inputs might be in use, and he wants to work with external gear, maybe FX, compressor, EQ and what not.

Therefore, he would most probably need three devices with a HDSPe MADI FX: 12Mic and M32 Pro II AD and DA.

Together with an HDSPe MADI FX we talk about a huge amount of money.

Next, he also wanted headphone outputs. The HDSPe MADI FX has one older design, the 12Mic has also only one. So you have only two, this is another advantage of my proposal/setup, you get already 4 high quality phones outputs and with a 12Mic on top, maybe in the future, you have already 5. Or add an ADI-2 Pro and you get two more high power outputs. You have one AES and two ADAT/SPDIF ports free for that purpose.

Therefore, I would advise to start the way I proposed and to gain experience what exactly is require and in what port quantities (in terms of Instr Inputs, Mic Inputs, AD/DA for external devices, MIDI, AES perhaps for a reference converter, etc).

There are newer more recent models available than those...

MADI devices can be connected either as single device to a recording interface or can be chained, one device after the other and back to the recording interface. Each device in such a chain needs/introduces a few samples delay for the forwarding of audio packets. Look into the Octamic XTC manual, there the delay is mentioned. 3 samples per device at single, 6 samples at double speed.

Regarding FX. In TM FX, every channel has EQ and dynamic section, but when it comes to delay and reverb, there is only one FX bus for that. What you can do is to use it like a send effect in a DAW and dial-in the amount of Reverb/Delay that you want from this send effect, but you can't use it as an insert. There you have 1 setting for all channels.

Regarding USB … It is not as inefficient as you think.
1. compare RTL, there is only a little difference between PCIe card plus separate converter
https://www.tonstudio-forum.de/blog/ent … cts-en-de/
2. Look at my last posting, where 99-100% CPU utilization still doesn't cause an USB based recording interface to break.
https://forum.rme-audio.de/viewtopic.ph … 92#p210092

You might have even more advantages by buying an UFX III.
Because this flagship interfaces might give you already all the ports that you need.
Plus, feature wise Autoset and DURec (as standalone or backup recording).
By Firmware upgrade, you will even get a Room EQ and Crossfeed. See the Posting about the Beta SW.

Even a UFX II without MADI might be sufficient, but if I were you, I would spend the extra bucks for the UFX III to be on the safe side, that you can expand using MADI if you require. Or to be able to connect an UFX III to HDSPe MADI FX, to be able to do that (whether it makes really sense or not).

In the old days when I was new to RME I also thought, that getting a RayDAT PCIe card and connecting an UFX to it would give me benefits in terms of latency. But this was not the case, it made it only harder in terms of operation and routing because I had to route all channels over ADAT and at the end to operate two different devices in two TM FX instances.

When you would connect HDSPe with UFX III via MADI, which would be possible, you would have the same operational "challenges" … to operate a HDSPe in one TM FX instance and the UFX III in the 2nd one.
Gent, sorry, but this is all too complicated. I would only connect an UFX III to a HDSPe MADI FX if I had it anyway and would like to use it solely for backup recordings.

But please do not make things too complicated.
If I were you, I would start with the UFX III and make experience with this USB3 based interface 1st.
You can still buy an HDSPe MADI FX on top whenever you like if you feel that you "NEED" to have it.

Regarding M32 converter and 12Mic. May I ask whether you REALLY need this number of channels? For recording a little and mainly listening to music, mixing and mastering an UFX III should be perfect. Now, even with Room EQ.

12Mic and two M32 AD/DA converters is around €9500 alone .. There should be a justification for this add-on cost.

So, could you kindly tell me how many analogue ports and what types of ports you really require?
Maybe we should start 1st to gather your actual demand.

A friend of mine just built a studio, and he has plenty of hardware FX (EQ, Compressor, Mastering devices .. Around 16 external devices). For him, an extension with an external AD/DA converter with 32 channels connected via MADI made absolutely sense. Also connected a 12Mic to connect all the mics to record the drum kit if his son.

But if you do not have this high demand for channels, I would try to reduce the setup to one or two devices like e.g. UFX III and maybe, if you like the features, the ADI-2 Pro FS R BE or perhaps ADI-2/4 Pro SE on top *roughly spoken* to just give an idea.

But now please let's talk about your setup, what ports are your real demands … Do you use external FX … etc?
What is in use now, where exactly do you feel a limitation?

Thanks for further information.

The difference.

If you connect external MADI devices to either UFX III or HDSPe MADI FX, then you see the additional ports of external preamps or adda converter as MADI channels in the ONE TM FX instance.

With two recording interfaces you have two TM FX instances, either in one or in two windows (TM FX: -> open new window).
But there is no backplane between them.
So you need to route channels between either ADAT and/or MADI.
Assumed the HDSPe MADI FX would be the main interface then the UFX III can either operate in standalone mode. But then it is cumbersome to operate things like Autoset or Mic gain.
So it would be better to connect also the UFX III via USB simply for operation.

Now the downside, you have to control the routing in two TM FX instances to route on the HDSPe MADI FX audio channels to the UFX III .. and also in the UFX III instance to route audio channels to the HDSPe MADI FX.
And this can become a little cumbersome.

Its easier to work with one card as then it is also easier to create submixes in submixmode.

Another idea, not sure whether you have a similar environment like me, where the PC is also the audio player

++++++ Living Room ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

ARC USB                                                                   Internet (DSL 250/45)
|                                                                               Fritzbox
PC with MusicBee Player Remote Plugin                    Wireless
|
|  +connect external FX like Lexicon Reverb unit if you need something like this
| /
UFX III---------------------------------------------------------<-----ADAT1/2----->(2 cables)---------------------------+
|                                                                                                                                                               |
ADI-2 Pro FS R BE                                                                                                                                      |
|                                                                                                                                                               |
+Geithain RL 906                                                                                                                                      |
+Audeze LCD-3                                                                                                                                         |
                                                         HighEnd HiFi-------ADI-2 Pro FS R BE-----Optosel 4:1---Ch1-----------+
                                                         "Main Out B"                                                                Ch2----TV
                                                                                                                                             Ch3----BluRay

Features:
- you can use your HiFi as 2nd pair of monitors for A/B listening
- High Quality D/A conversion in Recording Corner and at the High End HiFi with two ADI-2 Pro FS R BE
- Remote Control of MusicBee Player with Android Phone or Tablet via Wireless
- PC as Music Player using lossless FLAC files
- ADI-2 Pro features: Dynamic Loudness and Auto Ref level
               - using Bittest to ensure lossless audio transfer end to end
               - SRC if you have to integrate e.g. DAT recorder
               - if you want to integrate turntable, get ADI-2/4 Pro SE for the HiFi corner
- Oehlbach Optosel Mk II 4:1 switcher up to 192 kHz, you can switch between 4 ADAT/SPDIF sources
   has a nice remote control, looks good, also operateable at the device with one push button to switch input channels

I am playing guitar as well.
I have meanwhile a stereo setup with two Marshall combos, I think you saw that already in the picture above.

I used the UFX+ some time ago, since a couple of months I upgraded to an UFX III to also have fastest converters available.
To be honest, calculate it through ... on stage you have more latency between musicians .. that only as a side note.

I am using the UFX III for special purposes, e.g. as a parallel effect loop for the Marshalls to keep the punch of the signal, I do not like to noodle the sound completely through an FX unit ...

Signal flow: I plug my guitar to the INST input of UFX III.
From there, the signal goes through a booster pedal (Marshall Guv'nor) and further to the amp input.
From the left Marshall combo, the preamp out signal goes back into the UFX III and from there
a) straight into the two power amps (L+R)
b) to one of the two connected Lexicon PCM 81 (or alternatively the PCM 91)
The 100% wet FX signal coming from any PCM I add to the submix which goes to the poweramp section of the combos.
Finally, the two amps are being recorded by two mics on each amp (Tube Mic and SM57).

I never had any latency problems because the routing happens on the device itself. I do not route through the DAW.
From the DAW I only listen to the backing track to which I play and this I record.
This setup is absolutely no problem, no PCIe card required, it wouldn't change anything much.

The other advantage of this setup, I can record the direct signal from the guitar for re-amping purposes.

Lately, I got the hang of playing through a very nice amp VSTi. I can tell you that I have no lag playing even when using ASIO buffer sizes up to 128 samples. Even 256 would be possible, tried it in the past already. But in fact this is not required to have such big buffers. Usually, I use 64 or 128 samples. And this setup rocks...

Another advantage, by TM FX routing capabilities, I can use the two FX (PCM81 and PCM91) for either guitar or DAW or PCM81 for guitar and PCM91 for DAW. All is possible.

Two sound examples: see on this page: https://www.tonstudio-forum.de/blog/ent … iii-en-de/

Really, you do not have to worry about anything, it simply works. The new UFX III has converter with a very low latency. It also worked very well with the previous version, the UFX+, which had a little slower converter. I repeat: on stage, you have more latency between musicians than that. Take an Excel sheet and do the math yourself.

Yep gotcha Man!
I'll go for the UFX III
My latency reference for guitar through VST amp is Leon Todd (you know... one the best guitar stuff youtuber). I was in touch with him about his system setup for vsts amp demo and that guy was so nice to answer me that he use Apollo interface setted at 48khz and 64 samples with about 4ms of latency (but in a Apple domain). So to me 4ms with vst amps and some fxs is the latency goal.

Other topic, regarding instrument inputs and the very nice RME conversion quality, some sound example:

a) straight into instr input, no VSTi, no processing

This is a Gibson L5 CES from around '71 directly plugged into the instrument input without any VSTi and without any form of post-processing. Fully improvised, simply the guitar to a backing track from a friend (Wesley G.):
https://www.tonstudio-forum.de/attachme … -320b-mp3/
[ taken from this blog article: https://www.tonstudio-forum.de/blog/Ent … CIe-EN-DE/ ]

b) silent recording, guitar mic'ed

This is an overdub through my Marshall Combos, silent recording with volume peaks under 80dB.
UFX used as a parallel effect loop (Guitar being plugged into the UFX's Inst input). Fully improvised:
https://www.tonstudio-forum.de/attachme … orrow-mp3/
[ taken from this blog article: https://www.tonstudio-forum.de/blog/Ent … -DURec-DE/ ]

c) Guitar via VST using an external FX unit (Lexicon PCM 91, connected to UFX III)

And this playing through an VSTi (S-Gear 3) and using Lexicon PCM 81 as external FX. Fully improvised over Backing Track from MusicBee Player (lossless FLAC file), loopback recording of the UFX III headphone submix with WaveLab Pro:
https://www.tonstudio-forum.de/attachme … part1-mp3/
https://www.tonstudio-forum.de/attachme … part2-mp3/
[ taken from this blog article: https://www.tonstudio-forum.de/blog/ent … iii-en-de/ ]

Ramses, let me say how kind, generous and full of infos you are Man!
Just from the first answer till now!
Thank you so much Man to spend so much time and patience with me, you are a real resource of this forum!
Now i have a much more clear idea for my project!
I'll go with the UFX III that packet all the i/o type, converters, on board function (DURec, standalone) and even the MADI for future expansion (one other idea is to add in future an hardware digital mixer like the Midas M32 Live and a pair of digital stagebox via cat5 cable and connect the mixer to the UFX III via madi to get an hybrid software/hardware recording system).
Thanks again from Italy my Friend!