Subwoofer is too loud with gain all the way down

I'm not sure what to do to get the excessive gain out of my subwoofer. I have RCA cables (left & right) going from the Emotiva integrated amp output to the RCA inputs on my NHT Classic 10 subwoofer. I have a USB Micca Origen preamp/dac with the gain set at -10dB. I can't turn the gain on my sub any lower. My preamp volume is at 12:00 and my integrated amp volume is at 1:00. Thanks