Amazon.com: DIGITNOW 3.5mm 1/8" TRS to Dual 6.35mm 1/4" TS Mono Stereo Y-Cable Splitter Cord for Smartphone, Computer, CD Player, Speakers and Home Systems Amplifier, 3.3Ft : Electronics
1/4" Stereo Audio Jack Plug Adapter Single Male To Female 6.35mm Dual Mono Stereo Jack Headphone Microphone Y Splitter Converter - Audio & Video Cables - AliExpress
File:Jack mono jack stereo xlr male and female.JPG - Wikimedia Commons
Monoprice 3.5mm TS Mono Plug to 3.5mm TRS Stereo Jack Adapter, Gold Plated - Walmart.com
Are Guitar Jacks Mono or Stereo? – Traveling Guitarist
Amazon.com: TISINO 1/4 Mono to 1/8 Stereo Cable, 3.5mm TRS Stereo to 1/4 inch TS Mono Interconnect Cable (Mono to Stereo Adapter) - 3 feet : Electronics