It’s hard to beat this vintage reel for learning about how vacuum tube amplifiers work. It was put together by the US Army in 1963 (if we’re reading the MCMLXIII in the title slide correctly).

These amplifiers could be found back in the day in some form in most consumer electronics, and remain a spectacularly cheap way to boast a tube amp in your hi-fi even if it might not always be the ...

First made in 1959, this is the best-selling tube amplifier ... standard way of rating amplifiers’ power levels. But the ST-70 has remained popular among vintage hi-fi enthusiasts.

Do you really need a DAC that costs between $14,000 and $18,000? Bluebird Music thinks the Jadis Vacuum Tube JS5 or JS2 SL are both worth it.