Hi Greg -
Thank you for the quick reply!
I do understand the differences in signal levels. The references you provided explain the different levels, but do not address my question.
My problem lies in the internal connections the OS provides.
I want to use a specific program that is looking for a microphone input.
I use an external preamp to boost the microphone signal up to an instrument level, which allows me to use a switch to select between the 'mike' input and other higher level inputs before it gets routed into my audio interface to the PC.
The program I want to use doesn't see the input from my audio interface as a 'mike' input.
Any program that works with 'mike' inputs must be relying on the motherboard or soundcard to have already amplified the 'mike' signal to a level it can work with. I don't believe the programs are working with the low level microphone output signal.
I want to be clear here - I am not suggesting putting the amplified microphone signal into a "microphone" input on the PC. In fact I have turned off the internal motherboard sound system, because I use a high quality audio interface to bring audio into the PC on a USB line.
So it is a question of internal routing. How can I get a boosted 'mike' input found on a 'instrument' level input line to be accepted as speech by a program?