Where to find a 5.1 channel speaker system with optical input?

Your question tells me you do not know a lot about home theater equipment. In general - you need an AV Receiver that takes optical, coaxial-digital, HDMI, etc, and does 2 things: * Passes the video onto the TV * Decodes and amplifies the audio to drive speakers That last part is real important - speakers are MOTORS. They consume watts of power. Input signals like optical are ... information. These are called "line level" signals and cannot directly drive speakers. An Amplifier is needed to up-convert the signals with enough power to make sound. There are some exceptions: Computer Speakers - these often have built-in amplifiers so it makes hookups easier. Sound bars - These also have built-in amplifiers. So you can find Logitech computer speakers that take optical - but these are designed to surround 1 desk and feed sound to 1 person. Sure - you can try to run them at max power to try and fill a room, but plan on replacing the burnt-out system every few months.

You might want to take a lool at sound bars, most have optical in and some sound realy good I would recommend the Boston Acoustics Tvee model 25 but there are other sound bars that are also good...It sells for around $349.00