You could get an emotiva mini X amp for $219 then use a Apple airport express as your source plugging in directly to the input of the amp. Use the amps volume control on the front as a volume limiter setting it to the max volume you would want to ever hear. Use your iPhone to stream the music to the Airpot and control the volume from the iPhone, max volume will be set by the volume control on the amp incase you accidentlly swipe full blast on the phone. Also the amp has a auto sensing feature so you don't have to physically turn the amp on, just start the music and it turns itself on.
