How important is the tonearm?

Dear Davide, You wrote:
"As to importance, the tonearm is secondary to the turntable. A spring suspension turntable like Linn or Sota with an entry level tonearm will reveal much more than if you buy a better arm but compromise on a non spring suspension turntable."

I and many others, like Dan_ed, would strongly disagree with this wild generalization, to the effect that suspended turntables are better inherently than unsuspended ones. Can you amplify on this thought?

Lewm, i was in audio at the hey day of vinyl and my college education was physics. The assertion is fact based from comparison in the early 80's with reference systems in the $20K range, trying various TT solutions at the time, Rega, Denon, Sota and Linn Sondek. The basic reason why is this:

A vinyl recording is a physical transcription of the audio sound wave in a circle spiraling inwards. For absolute fidelity the stylus must trace the signal with no other superimposed vibration in the range of human hearing and with no sympathetic vibration from the tracing tonearm assembly. It is also a stereo ( or quad) signal so that difference in relative motion exists between left and right side of the stylus. These physically transcribed vibrations are the key to what we call imaging; the more exact they are followed, the better the tonal resolution (timbre) and the more we get a sense of instrument spatial location.

The problem with playing an LP is external vibration; you are vibrating right now in your seat (heartbeat, many other vibrations exist from motors, vehicles, building construction). Assuming that you have a top notch TT and tonearm so that it creates no vibration and does not vibrate sympathetically you have to filter and damp out these external vibrations from reaching your stylus playback or your stereo image collapses, low volume detail becomes vague, muddy.... basically the external vibration changes the electrical signal transduced from the stylus and it affects the oh so important low level transient detail.

Rigid, non suspended turntables like the Rega and Denon have mass damping chacteristics only so that even the best arm in the world can only bring so much into focus and less than perfect arms are small ships tossed around in a storm of vibration.

Turntables like the Linn and Sota when properly balanced have a suspension resonance point below the audible range of human hearing, vibration from the surface the TT rests on is damped by the suspension above the resonance point.
They are not perfect but they acchieve an order of magnitude greater success than turntables who don't use basic automotive physics for a soft stable ride. Because they dampout external vibrations so well before they affect stylus tracing, cheaper arms have a calmer environment to trace in and their deficiencies wont be seen without more extreme musical passages to excite the arm assembly resonance deficiencies.

I note also dialogue about whether to spend more money on tonearm or cartridge. note this metaphor... the arm is the chassis of the automobile, the cartridge is the engine. Its more fun to have a cheap chassis with a high powered engine than to have an expensive chassis with an underpowered engine. Cartridges have distinct sound characteristics, arms help refine and dig more detail out of the cartridge playback... they can't add what isn't there to begin with.

Ah, I see. We're not thinking apples and apples. Have you heard a modern, mass loaded, non-suspended table? I'm not talking about Rega, Denon, etc.

This is a question like what's more important...the preamp or amp. In my experience I have found that given arms with the same general ranking, the cartridge makes the greater difference than does the tonearm.