Hi Brent :)
hdspmixer does save and restore all settings correctly on my machine,
but alsamixer settings can't be stored for my RME HDSPe AIO.
FWIW the extension ".mix" isn't needed.
I experienced another issue. If I try to set a fader to 0.0, I only can
chose between -0.1 and 0.1, 0.0 isn't available.
Regards,
Ralf