Thank you for your input, Raul. I think the "perfect" VTF in that sense is simply a VTF that optimizes the performance of the cartridge over the wide(st) range of recordings, similarly to the VTA. Jon Carr determined that for some of his cartridges, this is achieved with a VTF of 1.75 grams, and I trust his expertise. I find that the way I perceive sound varies from day to day depending on many factors so the by-ear method does not always work for me. I'm also more of a set-it-and-forget-it kind of guy. I'm not a "tweaker"; I want to spend my time listening to music, not analyzing the sound of every record.
Also, it seems to me that by your logic, you could never find a "perfect" (or perhaps "correct" would be a better word) VTF for a cartridge unless you'd be willing to adjust for every record, which is surely not true. There must be a VTF setting where any given cartridge performs best, whether it's a range or a pint point value, all else being equal. Again, if a designer of Jon Carr's caliber tells me it's 1.75 g, I listen. It may not be the way many audiophiles do it, but it has worked for me and my Delos so far.
Also, it seems to me that by your logic, you could never find a "perfect" (or perhaps "correct" would be a better word) VTF for a cartridge unless you'd be willing to adjust for every record, which is surely not true. There must be a VTF setting where any given cartridge performs best, whether it's a range or a pint point value, all else being equal. Again, if a designer of Jon Carr's caliber tells me it's 1.75 g, I listen. It may not be the way many audiophiles do it, but it has worked for me and my Delos so far.