I use 2, 12 foot USB extention cables connected to my CM15A giving me a total of 30 feet and have had no problems at all. Just don't skimp on quality. My USB cable also runs about 10 feet along side a 120vac extention cord and still no problems. So I think either way will work for you, extention cord to CM15A or extending the USB cable. The more economical way would be the extention cord for the CM15A.
(http://www.bdshost.com/X10/lpup.gif)---(http://www.bdshost.com/X10/lpup.gif)---(http://www.bdshost.com/X10/lpup.gif)---(http://www.bdshost.com/X10/lpup.gif)---(http://www.bdshost.com/X10/lpup.gif)----KDR