I always have the bass volume on max and for those I think the volume was on 4-5, I haven't really taken it passed there as that's loud enough for just playing at home.
The battery compartment on mine rattles when it's up really loud, so I've just taken it off. Just checked and with the gain on 0 I can have the volume on around 6-7 and it's fine but much passed that and the speakers start getting a little bit farty, but that's not that loud.
With a guitar you can get it a lot louder and there's no farty noises when in clean, obviously with the gain up it distorts.
But as a little amp just to play around at home it is great, I mainly use it to record guitar but also play my bass through it quite often too.
I'll get some recording of my guitar as well so you can hear what it's like, I don't use the tone knob on the amp, I find that at 12 o'clock is where it sounds best.