hi there
im on sonar splt,each time i close & open sonar the audio driver bit depth keep re-setting to 16bit
my soundcard are a tascam us-122l(64bit-driver)
once sonar is open(project)i set it to 64bit and all is fine(it only re-set on re-boot sonar..
is this already apend to someone?
 
 

 
 
 
 
thx
martin

You need to realize that the 64 bit driver is the OS bit depth which is nothing to do with 64 bit audio. 
You can run 64 bit audio on a 32 bit OS. 
But that said generally 16 bit is CD format, and if you look at the specs for most audio interfaces the run at a max of 24 bit. Those settings are for RENDERING bit depth. your wave files will either be 16 or 24 bit.  

thanks Johnny V 

The bit depth through almost all audio interfaces on the planet is 24-bit. Try setting that to 24 and see what happens (the tascam us-122l is actually 24-bits). I honestly never realized that drop down was changed to go above 24, and no idea when or why that happened.
 
Your Tascam doesn't support 64-bit audio, so SONAR is most likely choosing a "safe" default on you (everything supports 16-bit).

I would also check to see what the sample rate bit depth is set to within Windows > Control Panel > Sound.