http://audirvana.com/?page_id=159
Audirvana fully works under Lion.
But as of today (10.7.3), Lion is not supporting Integer Mode anymore. As there is no information from Apple on a date for a potential fix for this regression, it is strongly recommended to keep a Snow Leopard partition to boot on to get the best results.
The solution will come with the upcoming 1.4 release of Audirvana Plus that’ll bring Direct Mode. Direct Mode will completely bypass CoreAudio, even its low-level layer, and thus reenable the buried Integer Mode, in addition to offer even increased sound quality.