Audio xlr-usb/preamp use
 

I just ordered a Focusrite Scarlett Solo (3rd Gen) XLR-USB adapter with a preamp for voice track recording on videos. My knowledge of ALSA and pulse is limited but my dynamic microphone needs increased gain and this unit is highly regarded. I don't think there should be an issue with it, but the company doesn't explicitly support linux, probably because we don't need a vendor-supplied driver.

I'm asking for confirmation that there should be no reason why adding this hardware between the Audio-Technica AT2005USB microphone (which works well) and the Slackware64-14.2 desktop should have any issues.

I searched this and found this.
Hope it helps (you to formulate your own web searches).

If I understand you right, you are adding a USB audio interface to an already USB-based microphone? That won't do anything, because you can't 'stack' USB audio devices like that. If the microphone can also be an XLR (as in a real analog audio device) source, and you have an XLR mic preamp built into the USB audio interface, that will make sense. As long as the USB device from Focusrite is USB Audio class compliant it should 'just work' as you say, but if the controls for things like gain/level are software based that may or may not work (if they are true hardware controls then its irrelevant).

Something else to consider: stand-alone mic preamps exist, and take XLR/TRS mic input and output XLR/TRS line level - you could hook up a proper microphone -> preamp -> line sink (and there are plenty of soundcards and USB class compliant devices that work just fine with ALSA for this) and have as much gain as you want. This would be the 'most best' way to do things, in my view, because a lot of USB-based devices are inconsistent in how they are actually controlled/interfaced to the machine - in other words, some gain/control/etc may expect a special driver or application, vs just being a full hardware solution and the USB Audio component is just an I/O device (as it should be). Also note that with multi-track stuff on USB you may not have each track 'independent' on the device - it may be hardware mixed prior to the I/O as a stereo source (USB Audio only offers so much bandwidth).

Note: I did not go look up detailed specs of either device here.