So, it turns out that the onboard audio on the Aorus Z390 motherboard doesn't have a live line-in. Basically, what I've done in the past is that I plug in my guitar amp simulator (a Line 6 POD X3) into the line-in port on my sound card, so I can hear my electric guitar through my computer speakers. Makes it really easy to record bits in Audacity and other stuff.
Now, when I plug it into the line-in on the motherboard, there's no sound coming from line-in, unless I check the box "Listen to this device" in Windows. Then the sound comes through, but the quality is so degraded and there's latency that it's not worth it.
My question is: if I buy a cheap Sound Blaster Audigy FX on Amazon to get a properly functioning line-in, a) does this pose any compatibility issues with the motherboard's audio, and b) would there be any other downgrade in sound quality going from the motherboard's audio chipset to the Sound Blaster?