I use it to boost the volume and gain up

First, it has independent volume and gain controls, which means that it operates more or less as a transparent clean boost with the Gain at "0" and the Volume turned up.

With the gain down, and the volume at unity, I can use this as a basic EQ pedal by changing the bass and treble knobs

Plenty of volume available for overdriving other pedals or an amp.

With the gain turned down and the volume up you get a very nice clean boost

With the gain all the way down, and volume all the way up, I can use this pedal as a clean volume boost

The Caline Pure Sky is built well on the outside but sounds compressed, harsh and the eq controls boost oddly (ie: bass also boosts/cuts volume)

The Caline Pure Sky is built well on the outside but sounds compressed, harsh and the eq controls boost oddly (ie: bass also boosts/cuts volume)

Note: should you wish it, this pedal can produce HUGE clean volume boost via the "Volume" control

I like the fact that there is a usable E Q to level out your tone