I noted that on this forum and the other one that there has been a few people note that the volume on the X-Terra's seems low to some folks. I use Killer Bs and noticed that I had to turn them wide open and the volume on the X-Terra 50 and 70 to get to where I could hear it pretty good. That said...the Explorer II I got came with the Koss UR-30 headphones. I tried those in the X-Terras and BAM...I had to back the volume control WAY off. Those are some great headphones for the X-Terras. I tried my B's on the Explorer and they worked great on it. So now I'm ready to roll. Thought I'd pass this along about the Koss phones though. Sometimes you see them come and go on the classifieds when someone gets them for free with a detector and doesn't want them.