Thank you Ron.
I don't really want to get into the "speed" issue with my XP25 here as we have extensively discussed this within our Boston group. I will say that the issue came up when a member of our group noticed that his digital, in his system, sounded faster on a number of recordings through his digital source than they did through his analog source. He too has the XP25 and suspected that the phono stage was the culprit. He asked me and Al to report back about the "speed" in my system as heard through my XP25. We found no issue in my system with respect to the "speed" of the XP25. Of course, not every system is the same.
Regarding arm height adjustments affecting the overall sonic performance of one's vinyl playback, all I can say is that anyone to whom I demonstrate this in my system hears the difference. They even hear it in their systems when I have offered to adjust their arm height. And they notice it when they are setting up their own vinyl front ends. Even though people hear the difference that slight adjustments to arm height can make, that does not mean that they are willing to spend the time to make the adjustments for each of their records. This topic is discussed a bit more on AudioNirvana where a few members do adjust for individual records. There are a couple of active threads discussing it now. (see this:
https://www.audionirvana.org/forum/...858-what-is-the-most-effective-way-to-set-sra). One thing that people listen for is the relationship between fundamentals and their harmonics. This relationship effects the perception of transparency, speed, and all sorts of other sonic attributes, IME.
You can refer back to David fine tuning Tang's arm/cartridge. He went back and forth many times to get the VTA and VTF set up to his satisfaction. I assume it was for the specific records he was using for his set up procedure. I just happen to do it for each record because I hear a difference and it matters to me. I want to be clear that I am not suggesting everyone do this. I will demonstrate this process to you when you come to visit and then you can assess for yourself if it "elevates the sound from 'slightly veiled' to 'more open and clear'." That will be fun.
I do not have a theory as to why other vinyl guys don't discuss this so much. Perhaps it is too boring a topic. Perhaps many people assume that once the arm/cartridge is properly set up, the job is done. Jim Smith told me that he never once entered a client's listening room and heard a fully optimized vinyl front end. I have no idea why that is. However, I will say that people do care about this because some are buying set up tools to try to squeeze more performance from their vinyl. Tang is discussing the fine tuning of his arm/cartridges based on the process that he learned from David. It seems to matter to him, though I don't know if he adjusts for different records. Christian discussed briefly that he adjusts when changing his various cartridges. They are both using David's "card" trick to repeat previous settings, so on some level it must matter. David told me that he has one setting for the majority of standard vinyl, and that he only adjusts arm height for 180-200 gram pressings. I think it does matter to people and they do hear the differences, they just don't seem to discuss the topic much.
Here is a question: if it did not matter so much, why are there many new arm designs (Axiom, Durand, Graham, VPI, Kuzma, etc) which make it very easy to adjust, and often repeat, arm height? If it were simply a matter of setting it up once, I suspect that these arms would have much more basic mechanisms for adjustments, and not the elaborate off set towers for easy and repeatable VTA.