After a considerable amount of work I now can use the B4 vst instrument under Linux. The setup is as follows: Fedora Core 1 + Planet CCRMA Wine-20041019 jack_fst-1.2 with Mark Knecht's hack for Wine-20041019 Native Instruments B4 However, when using B4 as a soft synth under Rosegarden it plays perfectly for the first playback. When I stop the sequencer and "rewind" to the beginning of the track and start playback again, B4 goes quiet. The B4 UI still works, I can see the B4 UI keyboard moving in sync with my midi keyboard, all controls work, I can see the B4 midi and audio connections in qjcaktctl, and Rosegarden shows midi traffic on the channel assigned for B4, but there is just no sound. If I kill the B4 window and restart and reconnect it, it works again, for one playback. I have tried reconnecting the midi and audio connections and I have set and unset the mute and bypass buttons in the VST window to no avail. B4 stays quiet until I restart it. I have tried this also without Mark Kencht's hack of jack_fst-1.2 in wine-20040505 but the behavior is the same in both cases. Any ideas what could be wrong? B4 works perfectly for hours when using it outside the sequencer environment, but I would also like to use it in Roseqarden. br, Timo .............................................................. MTV3 Laajakaista - Hauskemman elämän puolesta. http://www.mtv3.fi/liittyma/hankinta/laajakaista/