Next to Christmas carols, Sousa marches, and the collected works of Bobby "Boris" Pickett, there's no more seasonal music than bluegrass, which comes to life at the 30 or so major outdoor festivals and scores of smaller events that take place every summer throughout the US. As I write this, on the day after Thanksgiving, 2019's bluegrass season is only a memory, and the 2020 season is more than a half a year away.

As per our ritual, Karim and Dan arrived at my door in late afternoon, bearing our ritual's customary offerings: dark beer, wine, cold pork sandwiches, fruit and chocolate tarts, good music on well-recorded CDs, and audio hardware to try out on the host's hi-fi—on this particular Friday, my hi-fi. It's what we did: break bread while gabbing like regular folk about regular things, then bolt for the listening room for an evening of hi-fi fun.

In Herb Reichert's review of the original Schiit Audio Ragnarok integrated amplifier, he wrote, "Schiit Audio's Ragnarok [is] the first amplifier of my experience that plays earth and sky, mind and body, brown eyes and blue, speakers and headphones, with equal narcotic intensity." Herb's colorful conclusions so persuaded me of the Ragnarok's worth that, when Schiit Audio's Jason Stoddard and Mike Moffatt announced the impending release of the Ragnarok 2, I pitched a Stereophile follow-up review.

Hi-Fi: The History of High-End Audio Design, by Gideon Schwartz, Phaidon Press, 2019. 272pp. $84.97, hard cover.

The ongoing evolution of hi-fi can be measured in any number of ways. Most obviously, we see that evolution in the technologies associated with our industry: in big breakthroughs—mono to stereo, tubes to transistors, analog to digital—as well as incremental improvements in materials and manufacturing techniques.