Inside the ZENith Mk3 resembles a regular PC. It's in fact a desktop computer but heavily customized for sound quality. Glued to its bonnet is a large anti-vibration slab whilst the IEC inlet connects to a medical-grade mains filter. The power supply next to it looks like stuff regular gear runs on. This linear PSU was designed by Dr. Sean Jacobs of Custom HiFi Cables Ltd and incorporates a large toroidal transformer with three secondary windings connected to a PCB with rectifiers, a battery of low-noise voltage regulators fixed to a large heat sink, six big Mundorf filter caps and multiple smaller caps from Wima and Nichicon. The goal were three separate clean voltage supplies. A plinth with anti-vibration treatment houses an optical Teac drive on top, an Intel 1TB SSD below. If that's insufficient storage, more money can pursue 2/4TB. If you wonder why SSD, it's free from moving parts so better for the job, never mind offers substantially faster access times. A Mini-ITX motherboard by SuperMicro runs optimized clocks with all sources of EMI removed, embeds Intel's N4200 CPU and 8GB of Crucial RAM. These are all low-voltage quiet components yet sufficiently powerful for server duties. The digital outputs decouple with isolation transformers and seem to be powered from a separate line.
To simplify, Innuos created as noise-free an environment for their sensitive electronic parts as possible. Interference between parts, mechanical resonances and mains pollution all are known gremlins for harshness and grain which truncate sound quality. However, hardware must properly integrate with software which is just as important. It's why Innuos run a customized BIOS and extensively stripped Linux OS with LMS (Logitech Media Server) as music library. They cleverly baptized this platform InnuOS.
The product can work in five modes. If connected to a DAC via USB, it works as a server/streamer, relies on LMS and navigates through the iPeng 9/OrangeSqueeze apps on iOS/Android respectively. Or it can be used as an UPnP server for any standalone UPnP streamer from Lumin, Naim, Auralic, Linn, Moon etc. In this scenario Innuos suggest connecting your streamer to their own squeaky-clean streamer output, not your router/switch. The Zenith can also work as standalone Roon Core, Roon Bridge connected to a different brain or full Core/Bridge package. What it won't do is render UPnP. This meant that I couldn't control it through the Lumin app of my fidata. Team Portugal view LMS as more stable and with better integration of streaming services. Personally I use none of them but listed were Tidal, Qobuz, Spotify, Spotify Connect, BBC iPLayer Radio, Radio Paradise and TuneIn Radio Directories. Many more are still to come.
In my daily work, I roll with a separate router sans web access but in most scenarios the ZENith Mk3 will need it. At first I thought this mandatory condition a downside but it wasn't. In the event of failure, each Innuos can be remotely accessed, troubleshot and potentially rescued. That saves a customer from sending it back to a place of purchase. Besides, streaming services don't work without the Internet. It's only fair to admit that in this context I'm a fossil. Folks with the modern ways of listening won't be.