- http://www.synology.com/support/faq_show.php?q_id=392&lang=enu – Synology Knowledge Base: “What USB speakers and DACs does Synology product support?” (bad English)
- http://forum.synology.com/wiki/index.php/User_Reported_Compatible_USB_Speakers – strange wiki, you cannot get a user account there
- http://www.conrad.de/ce/de/product/872300/USB-20-Headset-Adapter – works with my DS213+ under DSM 4.3 – costs just € 10