Yeah, I would have thought it had more headroom than that.
I play with a LOUD drummer, so depending on what you play it may work for you. If you're looking at a Triwatt though their selling point is mainly being a lower wattage DR504, if you want headroom I'd just get one of the VHR kits for a 50 watter. The Triwatt DR channel sounded just like a lower wattage version of my Reeves, it was great. Again, my opinion may be skewed regarding headroom seeing as how I now play a Hiwatt 100 and am used to V4's and the like.