From Amazon
Cordial CFY 0.3 KPP Y Adaptor Cable 6.3 mm Gold Stereo Socket / 2x 6.33 mm Mono Jack Plugs 0.3 m Gold 6.3 mm Stereo Socket / 2x 6.33 mm Gold Mono Jack Plugs Length 0.3 m
Conrad Electronic
Cordial CFY 0,3 KPP Audio/phono Y adapter [1x Jack socket 6.35mm - 2x Jack plug 6.35 mm] 30.00 cm Black