A couple of questions from my side not knowing your complete setup and requirements.

1. What are the requirements to the new solution ?
    You mentioned so far: 12 analog inputs and MIDI I/O.
    As you are getting now a more modern solution, do any new wishes arise from that ?
    E.g. to be able to record also at double speed (88.2/96 kHz) ?

2. What about your other gear that needs to be integrated into the new solution ?
    What Mic Pres do you have and what connection possibilities do they offer (analog, ADAT, ...) ?
    Do you have any other AD/DA converter that could be connected by ADAT in stand-alone mode to re-use them ?

3. What is your maximum budget for that ? Open for new functionalities that can make life easier ?

Thanks for giving further information Matt. I understand your setup now much better.

Quick answer to your question to ADAT. This is an optical interface which allows two operation modes
ADAT protocol: 8 channels @44.1/48 kHz, but reduces channel cound at higher sample rates because of channel bundling
                        4 channels @88.2/96 kHz
SPDIF protocol: 2 channels @44.1-192 kHz.
Therefore many Preamps with 8 Mics have 2 ADAT output ports to be able to support 8 channels @88.2/96 kHz.
This transmission has the advantage to be fully digital without any loss over the wire.
The signal stays digital until it enters the recording interface for final D/A conversion towards phones or speakers.

So you are using an Echo Audiofire Firewire Interface with 12x Analog I/O and 1xMIDI I/O.
There you connect the 8 Analog Outputs of your M80 which serves as Mic Premap and connects your keyboard.
I assume you are using the M80's send/returns to insert the ACP88 into each of the 8 channels.

Computer <---- Firewire ----- Echo Audiofire 12 + MIDI IN/OUT
                                             12x Line IN/OUT
                                             ++++++++++++
                                              | | | | | | | |
                                              ++++++++
                                              8x Analog OUT
                                              Presonus M80<--- ACP88 inserted into each channel via send/returns of the M80
                                              8x Analog IN
                                              ++++++++
                                              Mics/Keyboard/Compressor (ACP88)

My proposal to you is to simplify the setup
- base everything on one RME recording interface like one of the flagship models RME UFX II or UFX+
- you can connect your Mics directly to the 4 Mic Pre's in front of the UFX II/+ which have an excellent quality
- keyboard can be connected to two of the eight analog ports on the backside
- in terms of compressor I would work "itb" (in the box) with VST plugins
  this allows you to record your signals unmodified which is better than to have the compression already in the recording
  then you can decide later in the mixing phase what compressor to take or what sounds best for the song / the instrument
  less devices, less cabling, much better SNR
- if you really want (I wouldn't do it anymore) you can also connect some of the analog ports of M80 and ACP88 to the
  remaining analog ports in the back of the unit or use the ACP88 as external compressor
- you could - if you want - sell the old stuff later to get a few bucks back to refinance, but not sure if this is your goal.

The RME UFX II or + will deliver to you RME quality and features, that you never had before
1. DURec - backup recording to USB Stick or Disk, can also be used for recording in stand-alone mode without DAW
2. Standalone capabilities, the unit is fully operateable via display
3. AUTOSET for the Mic Pres
4. Much comfort and flexibility by TotalMix FX
5. Comfortably working with the optional ARC USB Remote Controller which can be connected to either PC or can be attached directly at the back of the unit to a special USB port which is dedicated for this purpose
6. Two excellent phone outputs for you and e.g. a guest musician
7. Everything in one Rack Unit
8. 2(!)x MIDI I/O, so you can use 1 MIDI port for connecting devices and the other to e.g. remote control other RME devices
9. Possibilites to expand the setup using ADAT1+2 or AES

Totalmix FX is a highly optimized Mixer which is absolutely lag free.

On top of the solution you can download DIGIchecl which is an excellent audio analysis suite consisting of different analysis software modules, that run standalone on your PC and analyze audio directly as it comes in / out the routing matrix inside of the unit. This software is free of charge. One of the tools is a lightweight recording software called "Global Record" which you can use alternatively to a DAW if you need a stable recording and do not want to load a laptop with a DAW program with a heavy CPU/memory footprint.

As the UFX+ is not far away from the UFX II I would recommend you to take the UFX+.
This gives you the possibility to expand the solution in the future by using MADI which is a very nice option.
By this you have also two connection possibilities to your PC (in fact even three)
USB3 and Thunderbolt. The 3rd is USB2 (but then without MADI).
But it gives you a lot more flexibility to use either something which is USB based or something like thunderbolt which is in fact "external PCIe". This is then like using a PCIe card.

If you shall need it .. both Interface UFX II and UFX+ are using the new MADIface USB driver which allows very small ASIO buffersizes (which before only the PCI/PCIe interfaces had) down to 32 samples buffersize at 44.1/48 kHz.
The previous USB driver , that is also being used by the 802, had 48 samples as minimum. Still excellent, I only wanted to mention it.
Another thing is that the Thunderbolt driver has the feature "pitch" to be able to adjust / "pitch" the sample rate a little. This feature is not possibile using the MADIface driver, this in unsupported in the USB transfer modes of the MADIface driver.

UFX II and UFX+ have also the other advantage over the 802, that you can also save the Mic settings (phantom power, gain, etc) digitally in TotalMix FX. The 802 had in that regards another concepts for the friends of real potis.
I personally like the feature more, that you can save and recall a complete setup including routing and all gain levels that you use an hour a day or months before.

Sorry, but Motu I personally dislike, look in reviews where people say that they have laggy Operation Software.
Then they claim to have advantages becase they have insert ports.
With RME you can do this more generic / elegant by using the features of TotalMix FX to route the signals as you need.
You're mileage may vary, try both if you are unsure.

If you want to read a little bit about how I use the UFX+, even as tape deck without DAW, then you can have a look at a few blog articles of mine, one also contains the RTL (round trip latency times) of different RME solutions: https://www.tonstudio-forum.de/blog/ind … 8-RME-UFX/

In terms of driver stability I recommend you to read about my 400 track load test with over 800 VSTs in use using a minimum ASIO buffer size of 32 samples @44.1 and 64 samples @96 kHz: https://www.tonstudio-forum.de/blog/ind … cks-de-en/

These are the products I talked about:
UFX+: https://www.rme-audio.de/de_fireface-ufx.html
or
UFX II: https://www.rme-audio.de/de_fireface-ufx-ii.html

Optional: ARC USB
https://www.rme-audio.de/de_arc-usb.html

Ok, thats from my side, enjoy. If you have further questions, please don't hesitate to ask.