Gabo,

You can use up to three ufxs or ucxs together. We're you aware? Each plugs into a separate USB port but they act as 1 huge input into Sonar.

Just consider it.

gswitz
Gabo,

You can use up to three ufxs our ucxs together. We're you aware? Each plugs into a separate USB port but they act as 1 huge input into Sonar.
Just consider it.

 
Not sure about that.  Not sure where you are getting this information from.  It certainly does not seem to say anything like that on the RME site.  Usually it is not possible to connect more than one interface at once.  On the site it says it is compatible with USB 3 chipsets. Were you thinking you could connect to 3 USB ports.  That is not what they mean.  That means it is USB 3 compatible.
 
What I do like about RME interfaces is the fact they often have many analog inputs such as 10.  Plus the 2 ADAT ports increases the total input count to 26.  The other 4 inputs are via other digital inputs which one does not often do. e.g. SDPIF etc.. 
 
Most software cannot handle more than one interface at once.  Studio One can now though but only in that you are allowed to have one interface handling inputs and another outputs.  You cannot still sum all the inputs at once.  Although on a MAC I believe you can using an aggregate device setup. 
 
The UFX firewire port only runs at 400 speed.  I have been working with a borrowed Fireface 800 for a while and it runs at 800 speed which is damn fast.  I can get very low latencies with that model.  The RME Mic Pres are very nice.
 
The Focusrite Octapre or Audient are still good companion add on preamps.  I have been using a Behringer ADA8000 connected to the FF800 and it all works rather perfectly.  At my place of employment we are about to get the Clarett 8 Pre X and two ADA8200 preamps.  I suspect that will also all work pretty nice too. 

I have confirmed this also works with UCX devices but haven't mixed and matched. I'm pretty sure you can mix and match. By this I mean you can have a UFX and a UCX both working together.
 
In TotalMix in the upper right hand corner is a drop down. This will show each device and you can flip between them.
 
TotalMix does not allow virtual routing between devices, so if you are mixing everything to mains, you will have to send out of one device into another using physical cables.
 
You could virtually route between the devices using Sonar if you wanted to.
 
I'll tell the truth, it's a little complicated to have two TotalMix windows that are both active. It's a lot easier to have your heap of inputs come from a UFX and 2 related 8 channel converters sending into the ADAT inputs in your UFX. Then you get one big control window.
 
I will say, my favorite thing to do with my UCX when using it for live mixing is to loopback the ADAT and SPIDF. When I have less than 8 inputs in the gig, I can then use stereo compression and stacked EQs.
 
In this video I talk about it...
https://youtu.be/mAMp9MPAj3k
 
At the time I made the video I was only first discovering the possibilities (September 2014).
 
Don't forget that you can download and run DigiCheck which has great analysis tools.

Both ADAT and SPIDF can be looped back on the RME UCX (no SPIDF on UFX).
 
This means that you can plug in 8 inputs...
Route all 8 to SPIDF out with stereo panning.
 
Also Route all 8 analog inputs to ADAT Outs...
Route all loop-backed ADAT Ins to SPIDF out with identical stereo panning to initial 8.
 
Now, input FX like compression/expansion and EQ will be on both the parallel tracks.
One of the parallel tacks (the one going to ADAT) has 2 additional stages of EQ and Compression. The first stage is on the output of the ADAT channel and the second stage is on the input of the ADAT channel.
 
Now, you have parallel compression and as many as 3 stages of EQ on your tracks you send to the SPIDF output.
 
For your main mix, you have the EQ and compression on SPIDF output (which loops back to SPIDF input).
You have another level of EQ and compression on the SPIDF input.
You route the SPIDF input to the Main Outputs from your interface (say headphones 7/8 and Mains 5/6).
You have a final stage of EQ and compression on this final output.

Jeff Evans

gswitz
You can use up to three ufxs our ucxs together. We're you aware? Each plugs into a separate USB port but they act as 1 huge input into Sonar.
Just consider it.

 
Not sure about that. Not sure where you are getting this information from. It certainly does not seem to say anything like that on the RME site. ...

 
https://www.rme-audio.de/download/fface_ufx_e.pdf
 
See section 10 >> Using more than one Fireface UFX on page 25.

Caution... my posts kept getting deleted by the spaminator. I tried to break them up into smaller posts and hope they survive.
 
They are not in the order that I typed them in.

Using this loop-back method to stack FX in the UCX, what is the latency?

RME
How much Zero is Zero?
From a technical view there is no zero. Even the analog pass-through is subject to phase errors, equalling a delay between input and output. However, delays below certain values can subjectively be claimed to be a zero-latency. This applies to analog routing and mixing, and in our opinion also to RME's Zero Latency Monitoring. The term describes the digital path of the audio data from the input of the interface to its output. The digital receiver of the Fireface UFX can't operate un-buffered, and together with TotalMix and the output via the transmitter, it causes a typical delay of 3 samples. At 44.1 kHz this equals about 68 µs (0.000068 s), at 192 kHz only 15 µs. The delay is valid for ADAT and SPDIF in the same way.

So at 44.1, latency is 0.00024 seconds.
at 192, latency is 0.000045 seconds.

The reason I have tripled the numbers is that I'm describing a scenario where you

pass 1
  bring the signal in on the analog inputs and
  out through the ADAT outputs, and SPIDF outputs
pass 2
  back in through the ADAT inputs and
 out through SPIDF outputs (merging with pass 1 direct to SPIDF signal)
pass 3
  In from the SPIDF outputs
  and out to the mains

The timing of your parallel tracks will be off by 0.000068 seconds at 44.1. I can't hear it.
The SPIDF out doesn't have any phase dangers because you send the whole mix through it.

The biggest benefit of the SPIDF loop-back is that you turn your single 3 band parametric EQ into a 9 band parametric EQ at the cost of 0.000068 seconds at 44.1.
 
You can use the SPIDF loop-back without the ADAT Loopback. So, if you are recording 16 channels, you still get 9 bands of parametric EQ...
 
Lastly, the parallel compression thing can get tricky if you forget to align the pans between the input and ADAT channels.

Thanks Geoff I am surprised and impressed by multiple RME units to be used in tandem.  It was not that obvious from browsing their product description. That feature could be more visible.  Many would be interested in knowing that several interfaces can be used.  Great for expansion options.  Multiple main interfaces also would mean hopefully extra ADAT connectivity for each one, ADAT preamps being a quick and effective way to expand your input and output options. 

Totally is, Jeff. I think USB bus limitations make the UFX plus and madi expansion using USB 3 to be the path that RME thinks professionals should use. Especially if you really need 94 inputs.

I have some friends with RME gear, so we can get together to expand our capacity. I think that is the best practical use.

Honestly, engineers who practice teaming up can become a force in their local music community.

While TotalMix and the RME interfaces work well together in good circumstances, RME doesn't support it officially because too many computer related things can make it work erratically.

Sixteen inputs is usually enough for me.

There is a performance aspect for engineers. Packing in, setting up, capturing correctly, breaking down, packing out. Having a talented peer with you helps ensure everything works smoothly.

https://youtu.be/lTHmki4VyfE
 
I made a video about how to use the SPIDF Loop-back to stack the fx.