Meh, generally the more expensive stuff sounds better than the mass-fi stuff Best Buy will sell you. The prices go up faster than the "benefit" because the high-end stuff doesn't have economy of scale and/or is hand built (or at least isn't being churned off a non-US/European assembly line). Whether it's worth it to you/anyone is another matter entirely, and even those deep in the hobby have a cutoff point.

Pfft. McIntosh will sell you an amplifier with a 1 in front of that price (not that I would ever pay nearly that much for one) and you can easily double that price with other high-end brands. The Audio Research 160M monoblocks at $30K/pair come to mind.

Comes down to number of hours they're run, not how many years they've been installed. 2500 hours is a good rule of thumb, but if the amp is a conservative design (doesn't run the tubes that hard) you might get even more out of them.

Pre-amp or small signal tubes usually last even longer.

Try to get one that has other "colors" of noise. Some find white noise too piercing or only suitable to block sounds when they're awake, but find Brownian/"brown" noise more soothing for sleep, for example.

Cavalry. Calvary (also known as Golgotha) is where Jesus was said to have been crucified.

I would ask you to add Mitchell Leather to that list.

Family-run business in Milwaukee since the late 60s (when we were the leather capital of the US), hand made, artisanal level. And because they're small production they can source smaller batches of higher-quality leather than the "big boys" can get.

I've got one of their money clip wallets and love it, and my father has had one of their briefcases for the past twenty years and I'll almost certainly inherit it when he dies.

Not a shill, just a happy user of some of their products.