Big-name tube amplifiers ... on this kit for $10 or so. You can use the kit as-is if you just want a pre-amp, but it’s not suitable for headphone use out of the box due to its high-impedance ...

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.