The Vox AC15 is a 15-watt tube amplifier, which is considered to be a moderate volume level.
It can be used for gigs in smaller venues or as a practice amp, but in larger venues or outdoor settings, it may not be loud enough to compete with other instruments or ambient noise.
The AC15 also has a number of features that allow you to get the perfect sound for your gig, including a Master Volume control, presence and treble controls, and spring reverb.
It can be used as a stage monitor or mic-ed to a PA system, but it may not provide enough volume to fill a large room on its own.
The 15-watt all-valve combo amplifier should be more than loud enough for most gigs. However, if you’re playing in a large venue or you need a lot of volumes, you may want to consider a different amplifier.