Hello, first time poster here. Sorry for the longish post.

I have a fairly new Mac Mini M2 and a USB based audio interface. No need to name call here, but it is red in color. The computer came preloaded with MacOS Sonoma, and I use it strictly for audio recording and playback. For recording I am using Logic Pro and various guitar amp plugins. For playback I am using Roon. The audio interface I have has good audio quality and general features and I/O count that I need. However it also has some "quality of life" issues that really annoy me. I am looking at an RME Fireface UCX II to replace it. I have been reading about the quality and robustness of the RME drivers and continued support even after the device is not produced. I am willing to spend the triple cost needed to upgrade but only if it is truly more robust and reliable. To that end, here are some questions I have and am hoping you all can provide constructive feedback.

1) Time to switch sample rates: My interface takes 5-6 seconds to change sample rates and this is true even if the rate doesn't actually change. (i.e. "switching" from 44.1 kHz to 44.1 kHz). This is not a problem with Logic Pro since it is set once when the project is loaded. However, this is a hassle when using Roon for music playback. I have Roon configured to delay actual playback for 6 seconds to prevent missing several seconds of the beginning of each song.

Roughly speaking, how long does it take for the UCX II to switch sample rates?

2) Mixer not functional on high sample rates: The configuration software for my interface disables the mixer when the sample rate is above 96 kHz. I don't use such high rates in Logic Pro for my own projects, however there plenty of songs recorded in such rates that stream in Roon via Tidal. I have to specifically configure the audio interface to allow this and disable the mixer. Kind of annoying to switch back and forth.

Is TotalMix FX fully functional in all sample rates? Another other limitations that might exist here?

3) Misbehaving on system sleep: The configuration software for my interface becomes unusable when the OS wakes up from sleep. It is unable to communicate with the audio hardware. Interestingly the rest of the OS and all other applications can use the interface without issue. It's just their own homegrown configuration app that can't deal with sleep/wake operations. To recover I have to power-cycle the interface and re-launch the app. Sometimes have to reboot the computer, and sometimes have to re-install the application. Super annoying.

I have found some threads on here regarding issues with RME and sleep. How is the stability here with RME?

4) Attenuated line-in: I have a Mackie mixer that I use for CD player, cassette player/recorder, and a custom guitar effects unit that outputs a -10 dBV line level. I believe that the mixer main out is +4 dBu level but feeding that into line-in on the interface seems to attenuate the level considerably. Instead of boosting the input gain, I am compensating by increasing the output from the mixer. It seems odd to me and I don't expect anyone here to be able to troubleshoot that. From reading the documentation of the UCX II, it appears that the reference level can be changed for each input. If so, that might help me out here.

The customer support for my existing interface is generally responsive, but their effective responses have been yeah that's all by design, can't be fixed and I should prevent my computer from going to sleep. I am not pleased with any of those responses. The chatter on the Internet regarding RME seems pretty positive compared to other manufacturers. I am concerned that the sleep issue may still exist in some form and that I may trade one set of problems for another. I'm looking for an interface that just works as one would expect. If it costs 3X to get that, so be it.

Thanks for your input.