You might consider a newer mac mini with the fusion drive option as a less expensive alternative to a large SSD or SSD + conventional hard drive. The OS sees the fusion drive as a single drive but it combines a large-capacity conventional drive with an SSD section that serves as a high-speed buffer. In my experience the SSD section keeps audio streams moving w/o interruption and to accelerate downloads of high-res files. This has worked well in my audio-only system.
My mac mini connects by ethernet to a remote Classé CP-800 pre with built-in asynchronous DAC, an external drive for backups, and an ONT (similar to a cable modem) for fast downloads via a gigabit optical fiber internet service. I run JRiver Media Center on the mini, with the JRiver remote app on an iPad in the listening room.
My mac mini connects by ethernet to a remote Classé CP-800 pre with built-in asynchronous DAC, an external drive for backups, and an ONT (similar to a cable modem) for fast downloads via a gigabit optical fiber internet service. I run JRiver Media Center on the mini, with the JRiver remote app on an iPad in the listening room.