Have anyone tried to use the windows registered IO functionality with ASIO?

Yes, and there isn't much point. RIO signals either via a spin loop or by signalling an event. Very little use for ASIO in that, best just use directly, or don't bother with RIO which only really shows benefit on 10Gbit or higher NICs. Niall -- ned Productions Limited Consulting http://www.nedproductions.biz/ http://ie.linkedin.com/in/nialldouglas/