Tannoys are very hard to measure IME. They use a compression driver horn-loaded through the bass unit and as such are very directional at close distances. As such a tiny error in mic position, literally just a cm or less, will often show. I’ve done it many times and found it a really frustrating process and to be honest I think you’d need a jig to do it accurately.
Again very much IME the areas Tannoys are most likely not going to be right is in the crossover and compression-driver alignment region, i.e. right in the mid-band from about 1kHz to 6kHz. My favoured way of checking a pair sound pretty much like a pair is putting the drivers right next to each other and panning pink noise left/right. You really can hear if they are different. Any difference can often be narrowed hugely by very carefully tweaking the compression driver alignment, but it is a right PITA of a job and one with plenty of risk as the compression drivers are all but unobtainable. Anyway, that is the area I’d listen to the most carefully, though you will find it very hard to measure with sufficient precision to really trust the results.
