I use an Axe FX II XL for guitar recording. I use its analogue outputs for audio (at 44khz via my TC SK48), but it is also connected to my PC via USB for data control / editing functionality.
 
The problem is that each time I switch on the Axe FX, Sonar automatically kicks-out my TC Electronic interface drivers and switches to 48khz and the Axe FX USB drivers! All without asking me!
 
I then have to go back and manually reset everything (individually re-enabling 32 inputs!)
 
Is there no way to 'lock' Sonar's audio drivers / sample rate to stop them changing without explicit permission???

so your project is 44.1k?  and your TC Elec is set to 44.1k?  isn't there a mix control for the TC Elec that you can lock the source?

If you are using ASIO drivers only one device type can be active at anyone time.  By this I mean if you have two identical I/F's you can, with some drivers use the both, but in your case unfortunately not.

Have you unselected the AxeFX in Preferences>Audio>Devices?

I had a similar problem several months ago.
For me it was a windows thing.
Go to Audio Devices through Windows Control Panel and verify that both interfaces are set to the desired sample rate.

Maarkr
so your project is 44.1k?  and your TC Elec is set to 44.1k?  isn't there a mix control for the TC Elec that you can lock the source?

Project is at 44khz and TC is initially set to 44khz, but the Axe FX's DIGITAL outputs only operate at 48KHz.
No lock on the TC. The DAW takes over management of sample rate, buffer, etc. when it's running.

BobF
Have you unselected the AxeFX in Preferences>Audio>Devices?

Yes, the Axe Fx drivers don't even appear in the list normally (the Axe Fx is left off when I'm not using it).
 
However, if I switch on the Axe FX before starting Sonar (even after my interface is switched on), Sonar recognises the Axe FX as an audio interface, adds its drivers to the list, changes the sample rate to 48khz and disables all the TC interface drivers.
 
It did the same thing yesterday even whilst Sonar was already running. Usually Sonar asks me if I want to add the Axe Fx as an audio device and I select 'no', but it didn't even give me the option.

Base 57
I had a similar problem several months ago.
For me it was a windows thing.
Go to Audio Devices through Windows Control Panel and verify that both interfaces are set to the desired sample rate.

All devices / software are set to the desired rate, but that all goes to pot when I switch-on the Axe Fx (the digital outputs of which will ONLY work at 48khz).

Also annoying...
 
I just started-up the Axe Fx with Sonar already running and got the 'do you want to use this audio device?' popup. Fine - I just selected 'no' and Sonar stayed with my TC interface drivers and sample rate.
 
However, then when I turned the Axe Fx off again, I get a Sonar popup telling me the Axe Fx (which I'd opted NOT TO USE) has been disconnected, and do I want to re-route outputs (of which I HAVE NONE)!!!

Have you tried setting your rig at 48k just to see if the kids will all play nice?
I realize 48 opens another can of worms. My experiment with different sample rates resulted in a frustrated, hair-pulling, chair-kicking frenzy.