IMHO you can't compare the quality performance of two tonearms " per se " ( any ) because a tonearm is a " incomplete " product/item ...
I agree with Raul on this point, which "per se" can be extended to any component. You can't listen to an arm alone. You can maintain a stable system context and swap out a single component and compare those swaps, but there will always be other components within the system that *could* vary.
I agree, an analog front-end is a product of its pieces: turntable, turntable drive mechanism, cartridge, fastening hardware, headshell, tonearm, armboard, tonearm wires, phono stage, phono stage impedance resistors, tubes, etc. etc. If I'm off a half newton-meter of headshell bolt torque, from you, well ...
Not to mention the vagaries of semantic nuance even when we use the same vocabulary. "Tonearm X has superior top-end extension, asymptotically spinning heavenward with receding gossamer grace." (hmm... not bad, maybe i'll use that line.)
And then, we each have a different room. Not to mention humidity. Heh.
What does tonearm X sound like compared to tonearm Y? As the master says: "hard to predict all the variables are".
Yes, its a system. And yours will never be identical to mine. But lets never stop talking about it, the collective community of opinion is a joy.
And then, after all the headshell swapping, damping trough removing, and the four prelude passes ... after all the needle mr. cleaning, after the vta adjusting and antiskate donut twiddling, finally ... finally .... a record is played! Hooray!
Gawd, I love this hobby. Thanks to each of you for helping me enjoy it even more. honest! :-)
Tim