Hi Bruce, I too wanted just that and came up with my self-assembled Roon server doing just this. If you feel comfortable assembling a PC from its parts (motherboard, RAM, processor, power supply, etc.) this could be a very viable solution. Or maybe you have a friend or relative to give you a hand with this, should you feel that you’re not up to the task.
First, have a look at the HDPlex cases. For my Roon server I selected the H3V3 case, together with the 200W ACDC and 200W DCATX components for the power supply. These cases are nice, very well made and perform exceedingly well maintaining everything cool without a fan. Why fanless? Because if you wish to connect the Roon server to the DAC it means that your server will be close to your HiFi equipment and you’ll want it to be as quiet as possible.
Next, you have to decide upon a motherboard. As you want S/PDIF output (Toslink and Coax), you want a board able to output S/PDIF digital signal, so it should have S/PDIF output pins on the board. Looking for an adequate board I came up with the Asus Prime H310i-Plus R2.0/CSM which is a mini-ITX board with S/PDIF output pins and which is offered as ‘Corporate Stable Model’ which I preferred vastly over the many gamer boards offered today.
I used an Intel Core i5-8600K processor, I think now it’s easier to get an i5-9400.
I’ll skip RAM and disks, as those are the easy parts. The board connects up to four SATA devices, which can be spinning hard disk drives or SSD. It also has a M.2 connector for a NVMe SSD which is recommended for installing the operating system and Roon server.
I’ll show you though how to output S/PDIF from this custom-built computer. For this you need a S/PDIF output bracket like this one on Amazon. You connect the cable on one end to the S/PDIF output pins of the board, and on the other end to the bracket. It is actually quite easy. The bracket is equipped with a Toshiba DLT1151 fibre port for Toslink output and a gold-plated RCA port for coaxial S/PDIF output.
Roon will present this device to you as Intel HDA digital output, and you can connect your Roon server directly to your DAC using any one of the two interfaces. I am using Toslink out to my DAC which is a NOS DAC. I don’t do high res or DSD, so no problem. It seems you prefer coaxial output, which works quite as well and is very stable.