I don't live in chicago. Best way I have found personally. Use a solid 45hz tone turn the head unit up 2/3rds so if it goes up to volume 35 use approx volume 24. leave it on repeat at volume 23 to 24. turn the gain up on the amplifier till it doesn't gain anymore more and just turn it down a HAIR. there you go . pretty simple . DMM is a bit better but this way works fine.