I ran 480's for years with a 148, unless I was onstage I never had to use the attenuation switch, I always ran 0db. I also never used the roll off, it's best to do any roll off (if necessary) in post. You'll be fine recording most typical rock shows with the 480's at 0db & the 148 which is 20db, you may need to add a little from your recorder depending on where your levels end up. Great combo, enjoy!