just want to share my final solution for sync issues like arps or LFOs running out of sync, audio glitches or Virus losing sync when switching song positions in the DAW. Access recommends to use an USB hub for virus only. This recommendation is good, but still causes problems from time to time . Now I use a Thunderbolt hub (link below) with virus connected directly without USB hub to the Thunderbolt hub, which is connected via Thunderbolt to Macbook Pro. I think the syncing of audio via thunderbolt is better and more stable than USB, even the latency is improved. Furthermore the Thunderbolt hub is treated like an PCI express card and therefore is more reliable. On top the Thunderbolt connection offers enough bandwith (even TB 1 with 10 GBit/s bidirectional) to use the HDMI output of the Thunderbolt docking station to connect an additional monitor and also my audio interface Apollo Twin is connected to the docking station. Everything runs fine and my Virus never worked so stable and tight.