Monoprice 107128 3.5mm Mono to Stereo Adapter 3-Pack

The Monoprice 107128 is a simple but essential audio adapter that bridges the gap between mono output devices and stereo input equipment. The adapter features a 3.5mm mono plug on one end and a 3.5mm stereo jack on the other, allowing you to connect mono-output devices — such as certain microphones, instruments, or legacy audio equipment — to stereo headphones, speakers, or recording inputs. Without this adapter, a mono plug inserted into a stereo jack would typically only produce sound on one channel, making this small accessory a practical fix for an annoying and common audio compatibility issue.

Gold plating on both connectors ensures clean signal transfer and long-term durability by preventing the oxidation that can degrade cheaper nickel or tin contacts over time. The passive design means there are no batteries, circuits, or signal processing involved — the adapter simply routes the single mono channel to both stereo channels mechanically. Sold in a three-pack, these adapters are ideal for keeping spares in equipment bags, studio drawers, or at multiple workstations where mono-to-stereo conversion is frequently needed.