While I did not know how many speaker manuafacturers were specing distortion, I did know B&W does. In any case, my main point in this a case was more about understanding the system. Not much point in pursuing amplifiers that have really low distortion, when your speakers are order of magnitude worse. Anyway, good choice on your part.\n\nFTR I performed my own measurements with an Earthworks microphone and a low distortion analyser. \n\n\n\nAs for measuring speakers in a room, distortion is more of a relative measurement. Frequency response is clearly more of a direct measure and while the real challlenge is at lower frequencies, you make a interesting point about the impact of ceiling reflections. While they do impact FR measurement, there are major questions over their audibilty. If you have not already done so, suggest you read this https:\/\/www.audioholics.com\/room-acoustics\/room-reflections-human-adaptation or better yet, get Dr Toole’s book.\n\nI haven't read the entire book but I have read excerpts as well as many of his forum posts. Like most people with an audio system I've spent a reasonable amount of time trying to get the best possible sound at the listening chair, and to that end I regard his work as an invaluable reference. It definitely can't hurt to have some understanding of speaker and listening room interactions, to the point of being able to predict what tonal colorations are likely, but we're also fortunate these days to have an abundance of low cost tools to perform measurements and simulations. \n\n\nIn a more simple way, consider a performer playing a violin in your room. If your room treatment really improved the sound quality of the live performer, it may be worthwhile.\n\n\nBut how valid is the comparison between an instrument and a speaker, when the two radiate sound energy in very different ways? \n\nFWIW, I constructed my own convolver filter from live measurements to correct a dominant room mode at 38Hz and it made a big difference; removing a bass boom issue that was negatively impacting many recordings. However, high frequency reflections are not necessarily as measurable as they are audible, due to the fact that they impact more on time domain performance. \n\nI tend not to use much in the way of sound absorption treatment, but there are curtains, carpet and sofas etc that do reduce mid and high frequency reflections.