I always read everything.
This is exactly where a master volume is placed and you already have one...
This trick is used on amps without a master volume to be able to use them at manageable volumes.
On old tubes (valves) amps, it is very usual to add this master volume for this exact purpose.
Don't forget that if it's badly made, you'll get a lot more noise too.
And I would add that the Orange Bass Terror is badly designed if the master volume is useless at low to very low volume as it's really what it's intended for.