Taking a look at the ALSA code now; at a glance the loopback timer comes from include&#x2F;linux&#x2F;timer.h -- it doesn&#x27;t look like there&#x27;s any immediate dependency on a hardware interface or indeed any other device in the system. And I do recall using loopback without a hardware interface.<p>I would predict that the difference is actually in the virtualisation, the implementation of that timer may be very different to a physical or bare-metal machine.