I think I have to do the same thing when I switch to AUX. My phone volume is all the way up. When I switch to AUX mode I have to turn it up on via the steering wheel controls too. I dont think it sounds bad, but I wish the volume accross all the various modes would be consistent.
2005 BMW 330i ZHP 6MT. Built 11-19-04. Bought 4-2012.
Stock: Nav, leather, PDC, Xenon
Added by me: OEM Alarm, OEM heated seats, OEM aux kit, OEM Bluetooth, intravee, M3 strut brace, BMW Performance Intake, Nappa leather arm rest, updated LCM (triple blink, euro hazards, trifecta lighting, 3 stage brakes), temp gauge