Hi, I looked yesterday in kmix code and I see this, which I think is a bit wrong, or I do not understand why close() is called even if open fails - we just want to know if mixer is valid. bool Mixer_Backend::isValid() { bool valid = false; int ret = open(); if ( ret == 0 && m_mixDevices.count() > 0) { valid = true; } close(); return valid; } regards