Hi, I have recently acquired a Roland GR 300 and a Roland g707 as well as a 24 pin cable (new repro). I hooked up the 300 to the 707 with the 24 pin cable and a standard 1/4" cable from the GR300 to my amp. However it's not connecting - no sound. I must be doing something wrong, but I'm not sure what. Any help would be greatly appreciated. Thanks.