CME Matrix Y 4 Channel Headphone Amplifier with Unique Built-in Talkback Mic Unique TalkBack function allows everyone to listen to the same mic'd source through headphones 4 TRS 1/4" headphone jacks 2 1/4" line outputs compatible with balanced/unbalanced sources or external monitor speakers 2 /14" TRS line inputs compatible with balanced or unbalanced source 94.7 db dynamic range, 20Hz -20KHz frequency response