Which input should I use for an MP3/CD Player on my powered speaker? September 03, 2015 20:58 Updated Follow Always use the LINE in input on your powered speakers for LINE auxiliary devices such as MP3 players and Smart Phones. Related articles Where do I plug my microphone into my powered speaker? Cannot connect my bluetooth device to my speaker My amplifier's volume is extremely low Can I plug my wireless system into any audio input? I have a powered mixer...Can I hook up my powered speakers to it? Comments 0 comments Article is closed for comments.