We have no rules about the maximum volume at which you can play. That said, be careful when you open the doors, they play a big part in soundproofing the studios, and when you open them, if you have sound playing at maximum volume, it could be heard in the other studios that are potentially recording. 

From a health point of view, it is generally recommended to limit exposure to sound levels above 85 dB over a prolonged period, as this can cause hearing damage.