and Audball, bummer of the Kingston card problems. You say that you'll be looking for a new card. My current recommendation would be to stick with Marantz's recommendation of PNY or SanDisk. Although it is unfortunate that the 661 seems to be more picky about the cards compared to some other decks...
Yeah, I knew I was taking a risk. I'll shoot for one of the two you mentioned when I place an order later today. I'd be more bummed if tonedeaf wasn't there taping also to get the whole thing.
I do have a show Sunday night, though, and will need to use one of the Kingstons again unfortunately. Would it be best to format one of the cards first? Should I use something like THIS?
I'd have to agree with Jason and format formatting the card in the recorder.
The only time I've personally had issues is when I formatted my card in another device and used it in another. (formatted in my Cannon camera and my Nikon had a problem with it) They both use the same file allocation, so theoretically they should be compatible.
I only had one problem with the files on a card, I wasn't at home and wanted to clear the card/but save the data. I was at my parents and used my dad's pc, since I didn't have my devices USB cable I used my dad's card reader. The audio file was corrupt (last 8 minutes were digital static) BUT it was fine before (had played it back on the 671). When I tried to play it back after the transfer the file on the card was now corrupt.
It's only one experience using a card reader, I can't say that the card reader was definitively the problem, but I've never had an issue outside of that one example. I've seen too many people that have mentioned errors/bad cards and card readers at the same time, so personally I don't feel safe using one, I'll just stick to using the device and USB.
I'd suggest transferring only via USB and formatting in the device you intend to use, stay away from card readers or formatting on another device or pc if you can.