To point 1: related to what audio software one use and what exact apps are running in either foreground or background, such issues can happen with every interface probably. I recently had something like that which was related to DSP Quattro (audio editor) and another running app (don’t remember what it was).
Selected hardware was my RME Babyface pro! I suggest to check in what moments the sample rate issue happens and what software apps are involved.

I can only speak for Windows & RME ASIO driver. The sample rate changes immediately.
In this case, the recording interface is the clock master and the application tells the ASIO driver, which sample rate to use.
Even if the RME recording interface is clock slave to another clock SteadyClock technology ensures a very fast lock and sync to the sample rate and also removes any potential clock jitter to a high degree and distributes thus refreshed clock signals out on every digital output and Word Clock.

If you read closely (check the signatures), I am using Windows, waedi uses macOS.

I just validated it again by double-clicking to two auto-playlists in the MusicBee Player (a music player which supports ASIO driver). One autoplay list for single speed and the other for double speed music content.

I created them 1 or 2 years ago because I involved myself to convince the dev of MusicBee to invest some time to make sample rate changes possible in the software. As many people have music content in the library with different sample rates. As soon as a new song plays, the sample rate is changed immediately without a noticeable delay.

Otherwise, I know RME products very well and understand how Steadyclock works, that RME products can lock extremely fast to other clock sources. You can also see information about this in RME videos:
https://rme-audio.de/steadyclock-fs.html

I think waedi meant, it takes some seconds to open the FF Settings App AND find the Menu to select the new Sample Rate. :-)

I use a FF802 on Mac, Win and Linux... The Samplerate changes immediately after selecting it. The OS or App is not relevant for this.
Regarding Mac: In Audio Midi Setup, or in the FF Settings App or any other App (which has the capabilities):
If you select a new Samplerate, it just switches. Adhoc!

Maybe one Point, which ist Apple - related: If you have Logic open, the Projects Samplerate is the "King". That means, CoreAudio assigns the control of the units Samplerate to Logic as exclusive Master. No other app can access it until you "release" the device in Logic. Anyhow, this makes absolutely sense for me. But as you already had experience with Logic and Mac - I am sure, you noticed that yourself.

Another thing: You cannot control the IN/OUT Volume Levels in AMS or in the MacOS Audio Settings (The global MacOS Volume Sliders) with drivers installed and in USB Mode. The slider is just greyed out. But you can do this with Totalmix or in any DAW/App which gives Access to the unique channels.

Anyhow - if you consider buying a UCX II, maybe 2 Tipps:

1) Always a good idea is reading the manual before buying.
https://www.rme-audio.de/downloads/fface_ucx2_e.pdf

2) And Totalmix FX is free available for all. A nice feature is, you can set a "Offline Device" and "emulate" all units, choose UFX II there... and you can try out TM by your own, as you would have a UFX II connected...
Latest TM version 1.95 here: https://forum.rme-audio.de/viewtopic.ph … 55#p220555

BTW: It would be interesting (just for me) which interface you are talking about. No bashing or sth... Focusrite?

magie33,

My interpretation of what waedi stated is the same as yours. Time to navigate a UI does not count. It sounds like from subsequent responses that time to switch sample rates is nearly instantaneous from a human perception point of view. If so, then that's great.

Yes I am using a Focusrite interface. In fact I have two of them. A Scarlett Solo and a Clarett+ 4Pre. I have the Solo for laptop portable use. The Solo changes sample rates near instantaneously . However, the Clarett+ apparently (according to tech support) has internal relays it uses to switch out different circuits/chipsets based on the chosen sample rate. That's why it takes so long to switch.

I have looked over the manual for the UCX II. I posted my questions here because I wanted feedback from people with real world experience with RME.

ramses,

Yes this is the same in MacOS as well. All the various comments about how to select a sample rate in apps/drivers has added confusion to the discussion. The issues I have with my Clarett+ 4Pre taking 5-6 seconds to change sample rates is directly related to the hardware itself. What software is used to select that sample rate is not a factor.

That an application locks the sample rate is normal, how should a device support multiple sample rates?
Then the answer to his question is, that with RME he won't have any noticeable delay.

Thanks everyone for your feedback. I now have an RME Fireface UCX II being delivered today! After I spend time getting familiar, I'll report back with my experience with it.

Thanks for your effort, MusicBee is perfect for this use case!

Thanks, Jeff, very kind from you :-)