To be 100% i would have to be there. No other way. But taking an educated guess i would say halfway. Why just seems to be a good number, i havnt seen a decent amp clip before halfway yet during testing unless eq on hu wasnt flat. Why do you think i said find someone with an oscope? Just for reference my amp clips at about 5/8 gain on stock alt, 1 agm under the hood and just a big 3 with 5v running via rcas to the amp and this is with a lil over 2500rms so i figured he'd be fine with 750rms setting it halfway till he got to an oscope, unless he had his hu all the way up along with the bass on hu.