@lewm , that is exactly what I was saying in my last post! In my own experience every set up has to be "tuned" to work it's best particularly with bass and dynamics. I never use the calculation. I only use a test record during set up and I add mass to push the resonance frequency down as far as I can without making the set up unstable.
I would not know about different head shells because it has been a very long time since I used a tonearm that has a removable one. So, I would have to defer to you on that one. I also have never been able to AB tonearms in a way that I can say one sounds better or different than another. My sense is that all well designed arms with solid bearing designs set to the same resonance frequency with the same cartridge sound pretty much the same, like nothing. If an arm is adding or subtracting anything to the sound of the cartridge then in a perfect world it is not a good arm. It is not a perfect world and there are certain distortions added during vinyl playback that have to be minimized such as warp wow, miss tracking and low frequency rubbish. Until recently I did not realize how bad the low frequency rubbish problem was. I saw a series of oscilloscope traces of arm /cartridge combinations all set to the same resonance frequency. The lower the moment of inertia the less low frequency rubbish which lowered other types of distortion dramatically. The lowest was a carriage driven tangential tracker (very short arm) and it was hypothesized that this was the reason these arms sounded better.
There is no such thing as a flat record. There are low frequency undulations in the vinyl's surface that will deflect the cantilever of high mass set-ups creating a voltage. Lighter combinations definitely create less voltage as the arm is following the undulations better. This is the reason short arms are preferred. It was enough to talk me out of longer arms permanently. It might also be the reason in the end that the Reed 5T might sound better than the Schroder LT as it is a lot shorter.
Ducati, those are assumptions that many people including many recording engineers disagree with. Many prefer MM and MI types saying that they sound more like the master tape. They also require less gain creating a much better signal to noise ratio. Current mode phono stages might change this. The price of moving coil cartridges is driven solely by the market not by the "complexity" of manufacture. This makes MM cartridges a far superior value.
I am of the opinion that the simpler the phono stage the better. I think it is best to keep circuitry, switches and contacts to an absolute minimum. A tonearm should have single wires from cartridge to phono stage plug. Loading should be done with the appropriate resistor soldered in. One gain stage is better than two and so forth. Complexity is dangerous and expensive. No reason for it except that's what the market wants. If it is more expensive it must sound better, right?
