What supply are you using and what speakers?
I use a Paul Hynes regulated supply and Hawthorne Audio Duets. The Duets have two 15 inch drivers per channel (95db efficient) so the issue of not enough power never arises for me. I do appreciate that not everybody can accommodate such large speakers but going for efficient speakers removes a lot of potential difficult choices when putting together the rest of the system.
But as I said, it may be more gain you need rather than more power. As Seth says, you can run the ONE.2 etc flat out and there shouldn't be any problems with clipping. Here's a graphical representation of what he is talking about with the log pots.