SONICAKE QSS-19 Octave Guitar Pedal, Analog Classic Lower Octave Guitar Effects Pedal for Guitar & Bass, True Bypass - Octaver

Q: Does this pedal effect volume? i noticed it does not have a level knob

It does not affect the volume. I just played with the volume of the effect turned all the way down and clicked it on and off and the guitar signal sounded no different. You are essentially just adding in the "wet" reverb signal to the original signal. Actually, I never realized how quiet the switch is. Turned it up not playing anything and clicked it on and off and there is no click or pop of any kind.

Q: About to use w keyboard that has no mod wheel. Can I turn it on just for a single note to apply vibrato? Or will there be an audio pop...or latency?

When using with guitar and directly connected into sound system, i've been able to turn on and off with no pop, no click, etc. is heard through system.