Q: “What makes the E609 Silver ‘good’ for amps?”
A: The main things that make the E609 Silver “good” for amps are its sound and design. Sound-wise it has an extended frequency response that is contoured in a way that people seem to like on guitar amps. It can also take high SPL’s without distorting, which is necessary when used up close on a guitar amp. It has a hum-compensating coil to reduce electrical interference, which can certainly be an issue when used up close to a guitar amp. It has a hypercardioid pickup pattern, so it also does a good job of rejecting other sounds, which is especially useful in a live situation. There certainly are other microphones that work well on guitar amps; everything from the classic Shure SM57 to the Blue Dragonfly or the Royer R121 and a whole variety of other dynamic and condenser microphones are regularly used on amps with great results.
As far as the design is concerned, that’s where the E609 is a little more unique. In addition to its sturdy metal construction and use of a neodynum magnet, it’s a side-address microphone, so it can easily be hung over an amp or cabinet and rest right on the grill, without need of a stand. Not many dynamic microphones are built this way; notable exceptions are the legendary Sennheiser MD 409, upon which the E609 silver is based, and of course original E609 (while it’s less expensive, the silver model actually sounds closer to the MD 409).
Don’t be fooled by the microphone’s prominence as a guitar amp microphone, though, it also sounds great on other loud sources such as brass and drums.