I'm sure most of us have collected odd documents and books over the years relating to audio, DIY, measurements, or just things that seemed interesting or relevant at the time. Here's a few that I've collected. I have way more somewhere, but they're scattered and disorganized. I'll maybe add to it as I get things sorted out. I tell myself that I'll actually organize it all properly someday, but we all know that's a dirty lie. https://www.dropbox.com/sh/d7a9pho6d71doan/AAAXJBpws7IjS4ln1WoKU0RMa?dl=0 Here's what's currently in there as of 2021 July 5. There's a few old school textbooks there that may ping some interests, and I recently came across those books on vacuum tubes and cd players which are little treasure troves of info. The headroom file I've posted about before. Those who remember their old charting software, you could make custom comparison charts on their website. Well that file is all their raw data, including the unsmoothed graphs. I think I've gone through and OCR'd most of the pdf files (let me know if I've missed one), and some of them I've added bookmarks for easier searching.