PSB speakers are still voiced at NRC. Paradigm used to be based on NRC, then strayed, and now that the founders have bought them again they are returning to that philosophy. Paradigm also has double-blind listening rooms. Ascend is one of the few manufacturers to release a full set of graphs on their speakers, and they strive for "flatness."
And this quote from John Dunlavy, "Oh, no. Listening comes later. Because if you stop to think about it, no loudspeaker can sound more accurate than it measures. It may sound worse, or it may sound sweeter, prettier, but if we’re talking about absolute accuracy—the ability of the speaker to reproduce as perfectly as possible whatever’s fed to it—such a system can never sound more accurate than it first measures. So we try to get the greatest accuracy we can achieve from measurements. Then we begin doing what some people might call "voicing," because the best set of measurements are still open to interpretation." -- Stereophile, John Atkinson 1996
Dunlavy goes on to explain that last sentence as still trying to achieve flatness in small increments as well as large ones. Dunlavy speakers were widely regarded as some of the best of their time.
Many of the top studio monitors, like Genelec and Neumann, are flat as a pancake. It just makes sense to not introduce any artificial coloring when you’re recording something.
this is a good post that provides excellent context and background for what this pursuit is about - music reproduction that pleases the listener
accuracy in and of itself as an end is besides the point, it is at best a pathway to obtaining beautiful sound
reason being that a recorded signal fed through a system is itself usually imperfect, often emasculated, so it typically needs 'help' to get back its glory at time of performance or recording