Thank you all for usefull posts!
Yesterday I have bought a TI2 Desktop and in the first 10 minutes I have found this sync problem with ARP 
I have also MOTU 828mk3 (firewire) and I am always using the analog audio IN/OUT to transmit the audio signal. There is also a 828mk3 USB version. Advertisements sometimes say, that the transfer speed of USB2 and firewire F400 is almost the same. But the main difference is that USB2 transfer is always controlled by the host computer. In firewire connection both sides can control the transfer, so the connection is in final faster than USB2. So I can imagine, that routing 3 audio HiFi signals through USB2 could cause the sync troubles. I will try to disable audio over USB and let's see what happens 
Peter