Modem and small amp - mounted under desk. Modem is for Comcast cable internet. Small amp used to drive pair of speakers, but isn't used right now.

Switches! A 10 switch box that I built from a trailer hitch box, 10 DPST switches, a ton of wire and some split flex tubing. Controls the 'zones' for audio in the house, fed off the large amplifier.

The brains. Top box is the file server / movie streaming. Mirrored 1TB drives with a 40GB drive for the OS. Little switchbox next to it is the audio input for the large amplifier; music server, desktop, or aux cord, which feeds the amp on the bottom, which pipes out to the whole house. Middle machine, the dell box, is a free single-core P4 box from my old job that replaced an older single core P4 that I bought for $20 off Craigslist. It and the main server run Ubuntu server (no GUI). I can control the music server by cell phone through an app called Supersonic, which also has a web streaming interface too.

Main desktop, it's a quad core in an older Antec 300 gaming case (3rd machine in that case!). Has 7 hard drives! A 2TB, a pair of 1.5TB, a pair of 1TB, a 120GB SSD (Windows 10) and a 60GB SSD (Ubuntu Linux 14.04). Sub/speakers on desk are hooked to it, but can also use it for YouTube / etc throughout the house via the switchbox under it. 28" monitor, at least 5 years old now, but 1920x1200 resolution. A 4-port w/wifi under the monitor. The PC has HDMI output going to the other side of the wall with the display cloned onto my TV, and a 25 foot USB cable through the wall too, so I can play PC games with my XBox One controller on the TV.