The TD-20's "MIX IN" input on the back panel lets you connect an external audio player - (CD player, iPad, smart phone, etc.) This is convenient for when you want to play the TD-20 while listening to music at the same time. To do this, all you need is the correct cable to connect your audio device to the TD-20.
- If your audio player has an 1/8"(3.5mm) output connection, then you'll need a 1/8" - 1/4" stereo cable. This type of cable can be used to connect to your cell phone (iPhone etc.), or even for the Line output on your computer. One like this for example;
https://www.amazon.com/Hosa-CMS-110-Stereo-Interconnect-Cable/dp/B000068O36
-If your audio player has 1/4" connection for its output, you'll need a 1/4" -1/4" stereo cable. One like this;
https://www.amazon.com/Hosa-CSS-110-Balanced-Interconnect-Cable/dp/B000068NYH
Other cables are available as well, including RCA - 1/8" stereo;
http://www.amazon.com/Mediabridge-Stereo-Design-accommodates-SmartPhones/dp/B004YEBK66/ref=sr_1_3?ie=UTF8&qid=1377644969&sr=8-3&keywords=RCA-+stereo+3.5mm+cable
Once you have chosen the correct cable, simply connect the appropriate end to your audio device, and the opposite (1/4") end to the MIX IN jack on the back panel of TD-20. Then, turn up the volume and press play on your audio player. Make sure you have headphones connected to your TD-20 and both the MIX IN and PHONES volume levels are turned up. If you have the Main outs on the TD-20 connected to an external mixer or amp, make sure the mixer / amp's volume is up and the MASTER volume knob is up on the TD-20.
Note of Caution: Never connect the "powered" speaker output from an external mixer or source to the MIX IN jack. Doing so can damage the TD-20.