There are loads of boost pedals around at the moment, some offering tonal adjustment as well as boost, but on the surface T-Rex's Karma Boost looks as simple as it comes, with just a single knob that can deliver 16dB at full whack.
The pedal, though, offers non-linear boost so that the character of the sound will change at different knob positions.
"At around a 10 o'clock setting there's a nice, subtle lift that works well, transparently giving a driven amp a bit extra"
With the control knob set to minimum, there's no apparent boost at all, but at around a 10 o'clock setting there's a nice, subtle lift that works well, transparently giving a driven amp a bit extra for solos.
Further advancement of the knob gives you more of this, with a pleasing edginess and presence easing in at higher settings.
That extra presence is also there when used with a clean valve amp: the Karma boost won't turn it into a snarling monster, but it will drive it into a useful degree of breakup.
A tasteful booster with the added advantage of a buffer to make up for long cable runs.
