Two different countries are no problem. The IP-protocol doesn’t know countries.
But I had a problem with mirored sound under Linux with the sound buffer at 64 and network buffer at 128. every few seconds I got at least a second dropout with some garbled sound. After changing back to Sound Buffer 128 and network buffer at 256 it worked.
But my machine is old (i5, 1st gen.).
You might also want to disable the level meters after you have leveled in yourself. That reduces the CPU load by a substantial amount.