If you're talking about doing this after the fact (as opposed to patching a single soundboard source to both channels during a show), you can use Audacity to do what you want. Once you get it downloaded and installed (it's free), here's what to do (assuming you're starting with a WAV file): Start up Audacity, and open up the WAV file you want to mess with (i.e., click on the "File" menu, then the "Open..." item, then navigate to where the file lives, and open it up). You should see a pair of waveforms, with a block on the left side with info on the file (e.g., its name, "Stereo, 44100Hz", etc.). At the top of the block, right beside the file name is a downward-pointing arrow; this is a menu, so click on it. One of the items in the menu is "Split Stereo Track"; click on this item. After you do, you should see two separate individual waveforms, each with its own block of info to the left. In the block for the empty channel, click on the little "x" in the top-left corner to get rid of the waveform. In the "Project" menu in Audacity, click on the "New Audio Track" menu item. This should bring up a new, blank, waveform. Click somewhere on the other waveform (the one you want to have in both channels), and then press "Ctrl-A" (i.e., hold down the "Ctrl" key while you press the "a" key; this is a shortcut for "select all"). Then press "Ctrl-C" to copy the channel to the clipboard. Click somewhere in the waveform part of the other (blank) channel, and then press "Ctrl-V" to paste the original channel in. You're almost done. In the top (original) waveform block on the left, click on that little menu to the right of the file name. There's a menu item labelled "Make Stereo Track" (it's right above "Split Stereo Track"); click on it. You should now have almost what you started with, except both of the waveforms will be the same (as opposed to one of them being empty). Then go to the "File" menu and use the "Export WAV..." menu item to save it all to whatever file you want. Aloha, Brad