The Mbox will probably use ASIO drivers by default, but Audacity does not include ASIO support as standard, so you need to ensure that you also have Windows drivers installed for the Mbox and use those.
The Mbox will probably use ASIO drivers by default, but Audacity does not include ASIO support as standard, so you need to ensure that you also have Windows drivers installed for the Mbox and use those.