The CSP982 PHONESIT is a high-quality, Japanese-made connection device featuring A, B, and com terminals. You can use it to compare the sound of one source with two headphones... and because it's passive, the reverse is also possible. I have confirmed that you can input a sound source into com and listen through A and B. - Model Name: CSP982 PHONESIT - Brand: CURRENT, INC. - Country of Manufacture: Japan - Connection Terminals: A, B terminals, com terminal https://current.shop-pro.jp/?pid=134340729 Thank you for viewing.