Just had an aux input with iPhone adapter installed on my '03 JBL 10 speaker system at Best Buy. The sound sux!! Unacceptable to me. Stereo sound is bad (not good separation) and volume is low. Know I must turn my iPhone up to max for headphone plug, but still not enough. Is there a quality difference in these adapters? I know with the JBL it's all or nothing with the head unit, amplifier, and 10 speakers. Or is there a replacement head unit? What are my options? I don't want to pay huge $. Please help.