Adjusting Latency

No mention of buffer sizes, just a menu option "Set Latency" in the mixer software. It provides a choice of 6 discrete settings:
Minimum, Low, Standard, Relaxed, Safe, Extra Safe
On my system, these equate to values:
1.8ms, 3.3ms, 6.2ms, 12.3ms, 24.3ms, 48.3ms.

I like this. It's easy to switch back and forth whenever necessary.
 
EDIT
I have found that the lowest setting won't work in large projects, i.e. the audio engine stops. The next one up works fine though.

Preamps
Finally I've now tried the mic inputs for the first time. I used a brand new SM58. The signal was a bit quiet even with the level control turned up full, but it sounded good. I tried routing the signal through the second preamp at line level. It sounded nicer still. These preamps produce a pleasant smoothing effect when driven a little.

I have an Audient ASP 880. Similarly, I find the gain to be a little less than some of my other devices turned up to full. That said, it is totally sufficient for digital recording and the range of values available is more appropriate.

I like this aspect.

I'll bet you can do the same with the id22 that I do with my UCX.

Plug the ADAT out into the ADAT in. Now you can send channels and apply FX and mix together for parallel FX processing in real time.

gswitz
I'll bet you can do the same with the id22 that I do with my UCX.

Plug the ADAT out into the ADAT in. Now you can send channels and apply FX and mix together for parallel FX processing in real time.

 
I'll look into that.

But I believe that I can do parallel processing anyway without involving the digital ins or outs.

Nice... the onboard FX allow you to mix in a percentage of the original track?

On the other hand, your idea seems good, as it would enable parallel processing of a stereo signal. With the limited analog ins & outs I can only do it for a mono signal.

gswitz
...the onboard FX allow you to mix in a percentage of the original track?

 
The are no onboard effects.

Ah... well, if you are going through Sonar, you can do anything you like. :-)
 
For me, I have EQ, Compression, Reverb and Delay all within the RME UCX. I can do parallel EQ (effectively a way to expand or compress the eq settings with faders, changing them all to be more or less grave together moving a fader), or parallel compression on any track or stereo track. I can also stack EQs. 
 
The RME EQ has 3 bands or nodes that you can use as peak or shelf or high cut. Every eq has an additional low cut. you can copy settings between channels. you can reset any given EQ or compressor. You can save favorites and bring them up in different channels or on different nights.
 
You can save an entire mix, but re-using it would require you to plug in all the instruments the same way next time.
 
Anyway, the beauty here is that all this work has really 0 latency. No latency that a human could notice. It would be measured in samples. 
 

"RME UCX Manual"
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 UCX 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.

Mono button
One feature that I like is the ability to toggle back and forth from stereo to single-speaker mono by means of a button on the device. I use this a lot.