I just finished setting up and optimizing a Jamulus server on an Odroid n2+. It is a rather fast yet very power efficient board, with a CPU with 4 fast cores and 2 slower energy efficient ones. With this setup, if I connect through my local network I can set the jitter buffer to 2 local 1 server and get absolutely stable results, with both to 1 nearly stable. This server should be fast enough for about 20-30 people, but I have not tried that many yet. Running idle, it should consume less than 2 Watt....