So I was going to start on measuring my horns this weekend, but Murphy reared his ugly head and my laptop with all my software is dead, as in won't finish loading Windows. However, as I have actually never ran measurement before, I was hoping to clarify the setup. I was planning to use ARTA, but I have other software too. I am not really certain about the loopback part. I get the laptop to soundcard to amp to DUT and mic plugged into soundcard, but what exactly is the loopback for? Is it necessary? My amp doesn't have preouts, so this is a concern. Also, in regards to gain while measuring. Should the gain on the mic input be turned all the way up? How about the amp? That is probably going to be deafeningly loud.