Even about two orders of magnitude further than that, based on the work done so far.
For instance, 22.5ms latency has been achieved at a distance of 900 miles (between the middle of Kentucky and Boston) with SoundJack and this setup:
Both port-forwarded, both using Fast Music Boxes, both on fiber internet connections. First user had an MXL770 XLR mic and an Audient EVO4 interface. Second user also had an XLR mic and an audio interface.
For instance, 22.5ms latency has been achieved at a distance of 900 miles (between the middle of Kentucky and Boston) with SoundJack and this setup:
Both port-forwarded, both using Fast Music Boxes, both on fiber internet connections. First user had an MXL770 XLR mic and an Audient EVO4 interface. Second user also had an XLR mic and an audio interface.
San Francisco is 7 miles wide.