Part#1 Input-output level imbalance Part#2 oscilloscope and soundcard

New user here,
Part#1
I have UMIK-1 which connects to my windows machine, for soundcard I use my VEGA G2.1 DAC that has a USB input, the VEGA G2.1 is connected to my amp and onto the speakers.
I can't get the the input and output to match unless I control the output from REW to 24db and the input control set to 1.
Is this something I need to "fix"? If so how do I go about it? The microphone doesn't look like it has the capability to adjust the gain, and in windows I am already at 100%.

Part#2
Is there a how to for setting up a soundcard so it can be used to send the input signal to REWs Oscilloscope?
buy something of the shelf would be ok to, just not an oscilloscope


TIA
Astolfo

I was referring to some information on how to use a sound card to measure impedance for example.