What Does a Cartridge Compliance/Tonearm Mass Mismatch Sound Like?

Tom, I think the reason why you find Stringreen's metaphor a bit confusing is because, with all due respect to String, it IS a bit confused. I think possibly he is referring to an analogy between a high compliance cartridge and a lightweight, agile sports car, on one hand, and a low compliance cartridge and a truck, on the other.  Think of the cantilevers on these two groups of cartridges as the spring suspension in the respective vehicles. The compliant sports car suspension will sag down to its bump stops with a heavy load, like that of a high effective mass tonearm, and vice-versa for a truck with a very light load, analogous to a low effective mass tonearm; it will start to fly around on turns and bumpy roads.

What I don't understand myself is why my high compliance Acutex cartridge (cu = 42 according to Acutex specs) and my high mass Fidelity Research FR64S tonearm, albeit with a light weight headshell, sound so good together, with none of the typical symptoms of a compliance/mass mismatch. I keep waiting for something bad about this match to make itself evident, but not so far.

Dear @lewm : Resonance frequency is an important parameter to take in count in the cartridge/tonearm combinations however and at other priority levels is the self cartridge tracking habilities, the kind of design and materials used in its suspension and how well the cartridge designer damped it overall.

The Acutex is a champ on that critical cartridge design target: very high tracking abilities and this characteristic makes a difference on the thread's subject.
Btw, that Acutex cartridge sounds good no matters wich tonearm we are using but if it's matched with better tonearm its quality performance level can goes higher.

Regards and enjoy the music,
R.

Dear @moonglum : """  can appear to split into 2 separate voices one in each channel! """

Could you tell us with what cartridge/tonearm combination and LPs experienced that specific situation?

Regards and enjoy the music,
R. 

stringreen, maybe you should have responded to Dodge using Viper in your example instead of Porsche.

Oh wait, doesn't that already have a truck engine? ;^)