I just bought a Maz18 NR head and then the band I play in broke up.
So I have been using the Maz at home & yes it is very loud... but it sounds good at low volumes & if you get a Brake lite or something similar you'll be fine.
You can play it at home and it will work just fine, but try taking it to the music hall at your local college late at night and really open it up, you will see that playing it at home is nowhere near as satisfying.
Too loud for house ? Depends on the house and neighborhood. Definitely was too loud for my house ! I live in a mobile home park. I have a VOX AC15C1 that is much better for my house, church and rock gigs. YMMV...
great amp and I had one for a year or two but I ultimately decided it was indeed too loud for my house. loudest 20 watts I have ever heard and I strongly suspect it is conservatively rated. It seemed much louder than my Swart Atomic Space Tone or Suhr Badger, for instance.
the Brake-Lite is very effective as is the original Air Brake but for me it became a struggle with volume as I kept wanting to turn it up but it became painfully loud. I didn't think it was exceptional at lower volumes--certainly very good but clearly likes to be turned up pretty loud IMHO.
With it's very good Master Volume, and with the addition of an Airbrake or Brakelite, you will likely be fine as long as you are not chasing amp derived overdriven tones. It takes some volume to get into that zone, like most amps. These amps take pedals like no other though, so you can achieve alot of tonal possibilities at lowish levels with an O/D pedal out in front. However, the MAZ18 can be very very loud when called upon to do so.
The truth is that even the Mini-Z, at 5 watts can be dialed up to be too loud for the house, but the built in attenuator pulls it back enough to be manageable.
It likes to be turned up. you can get decent cleans, and decent light-crunch tones with the MV, but for real grind and bigger, fatter, more "open" tones (clean or dirty), I'd recommend you use an attenuator at home. I do all the time.