To say the least. I pretty much could never get it past 2-3. What's worse is that while it had a master volume, it was so dry when you tried to OD it (SS pre-amp). Headroom for days. I just wish there was a decent OD pedal at the time. I would have MUCH rather gone down the Marshall path to do it over again.
I saw a show years back where the guitarist of some indie band was using one of those and it was insanely loud. His tone was super bright and drilled straight into your skull. And he wasn't using an extension cab! Just the combo. Crazy volume. So much so that I've never forgotten it.