Where do I find the 6in pin to 6in pin IEEE1394 cable or 6in pin to 4in pin cable, 400 firewire, I went to Best Buy but all they had was the 9in pin to 9in pin 800 firewire connection, in which i was told would not work. I have the Yamaha Motif XF 8, which will be connected with the FW16E to my iMac that has the thunderbolt port. I was searching on eBay, but wasn't sure exactly what to get.
Two facts:
Your iMac has a Thunderbolt port.
Your Motif XF's FW16E has a 6-pin FW port.
What will make this connection:
You need a cable from "6-pin" (sometimes called 400) to "9-pin" (also called 800). Get the length you need.
You need an Apple adapter to take the 9-pin and fit it to your iMac's Thunderbolt port.
Links to example solution:
_ 9-pin to 6-pin cable
_ Thunderbolt-to-FW Adapter
Firewire and Thunderbolt are 100% compatible - you simply have to adapt the connections. You can find less expensive cables (get the length you require), but as with all things Apple, their adapters are to Apple spec (no shortcuts). The 6-pin to 9-pin FW cable is pretty standard stuff... I recommend the Apple branded adapter simply because they always meet and exceed their own specification on adapters!
Thanks for your support Phil!