http://www.youtube.com/watch?v=lxS0ddULd_Q&fe … player_embedded

poor English, but maybe you met these problems if tried H/W OPL passthrough.

used Hoontech Soundtrack Digital XG (YMF744), recorded music with Stereomix of this card.
OPL Music in the video is a little noiser than as real hearing. (especially using percussion)

If you are first time to use this feature, you must bear it as this video shows. 😢 😢