There are firmware updates on Tascam's website but no drivers I can find. I was trying to update the firmware when the original problem surfaced ( device not recognized by the USB bus).
It's probably best at this point rather than fooling with firmware, to contact Tascam support and ask them to help. A bad or misfired firmware update can render a device useless. I suspect it's not Mavericks or drivers that are at fault.
I contacted Tascam and asked if they had a driver that would perform with Mavericks. It is not mentioned on their specification sheet. I'll see what (if anything) they have to say and let you know. And THANK YOU for your help.
Shop for your Apple, Mac, iPhone and other computer products on Amazon.
We are a participant in the Amazon Services LLC Associates Program, an affiliate program designed to provide a means for us to earn fees by linking to Amazon and affiliated sites.