I am using a Presonus 1818VSL . wondering why only the odd # channel inputs are displaying on the inputs setting menu and the channel inputs list? Not that I use all 8, but for future projects would like to figure his out...thanks

Left AudioBox ASIO Mic/Line 1 = channel 1 on the interface
Right AudioBox ASIO Mic/Line 1 = channel 2 on the interface
Stereo AudioBox ASIO Mic/Line 1 = channels 1 and 2 on the interface
Left AudioBox ASIO Mic/Line 3 = channel 3 on the interface
Right AudioBox ASIO Mic/Line 3 = channel 4 on the interface
Stereo AudioBox ASIO Mic/Line 3 = channels 3 and 4 on the interface 
and so on
 
All the interface channels are available.
 

Wow how simple is that....! Thanks. Like it might kill them to match the interface #'s...!! 

That's basically how every Audio card works Charles.
My Focusrite lists the same way. It's the left/right or stereo routing. This is the norm.

My MotU also works the same way.

As does my RME.
All the best.

I probably knew that or should have ...until recently I used a 2 channel Focusrite and the right, left channels could only have been interface 1 and 2. Then this 8 channel threw me off . Thanks!!