My question is....does it get loud ENOUGH or does something just seem wrong? Does one unit start to clip or crap out before the other when you get to higher volumes? If it seems it gets loud enough for listening and even when you want to go a little nuts, the unit is OK?? But if something seems awry and if it is too low for normal or occasional crazy listening it's an issue with the output level and you may need to dig deeper, at least compare specs as is suggested.
Another guitar amp story, but relates to this situation..the Fender Hot Rod DeVille is a newer design, 60 watt tube amp that gets to max volume between 3 and 4 on the volume scale. Story is they wanted kids in music stores to bang on it, see how loud it got on only 4, and think, holy crap, think what it will do on TEN when i get it home!!! Unfortunately it had little gain after that and pretty much topped out. It was a good amp but a bit of a fraud, hard to control for serious players and didn't have the range on the control pots you really need. It was all in the way they had the preamp stage set up. I am reminded of the Spinal Tap Marshalls that went to "11."