«  Simple and effective ++ ++ »

Clean booster effect really neutral with the opportunity to strengthen moderately treble via a small cross. Although gradual effect setting whose activation is indicated by a blue LED.
I bought in kit version deluxe version which gives the assembly to choose between two versions (bypass or buffer).
The price shown is the Deluxe version (premium components) work with "mache" (missing more than welded). Great tutorial online and in addition they respond to emails, so ...

UTILIZATION

Use could not be more simple, no need for a manual ...
Knobs addicts spend their way. Simple and effective, that's all.

SOUND QUALITY

Truly neutral and possibility of adding a hint of treble. Knob with wide range from 0 (no effect even if enabled) to the cleat (max effect). I use it usually halfway solos (strat and tele) in addition to an OCD overdrive.

OVERALL OPINION

I hesitated with the Spark base before the plunge. No regrets for now. Moreover, the fact of the assembly ensures quality welds and longevity.
Just a "regret"; an additional inverter on the case the liberty of not having to choose between true bypass or buffer but to have both as needed.