The TS9 is, just like its sibling the TS808, a pedal classic beyond the ordinary.
A pedal that is widely used in all styles of music worldwide, by both professionals and amateurs. The Ibanez Tube Screamer series is the benchmark for how overdrive pedals should sound, the world's most copied sound.
The pedal works both as a single overdrive source or as a boost pedal on an already overdriven sound. Alone you get from a marginal crack (almost clean until you cut a little harder) to a moderately overdriven sound with a huge hang without it being hugely distorted or excessively compressed.
As a boost pedal, it presses quite hard if you want and the result is, of course, depending on what kind of sound you are boosting. Many metal records are recorded with a TS pedal in front of the amplifier.
As a single overdrive source, it doesn't have enough gain to be a metal monster. Then TS is for a completely different school. Powered either by 9 volt battery (included) or external AC adapter (sold separately).