Why the LP playback system is so important

The LP playback system's job is to extract as much musical information from the LP grooves as possible, and with the greatest fidelity to the signal cut into the LP. Any musical information not recovered at the front end of the playback system cannot be restored later in the chain. It doesn't do any good to have superlative electronics and loudspeakers if you're feeding them a poor-quality, low-resolution signal from an inadequate LP front end. If the music isn't there at the start, it won't be there at the end.

Why the tonearm is the most influential component in a high-end system

The ideal is that the movement of the stylus in the groove creates an electrical signal identical to the one that originally caused the cutting head to engrave the groove in the lacquer. That can occur only if the cartridge is correctly aligned with the record, so that the transducer elements move as the recorded signal is intended to move them.

The tonearm's job is to hold the cartridge over the record and keep the stylus in the groove. We want the tonearm to be an immovable support for the cartridge, yet also be light enough to follow the inward path of the groove, track the up-and-down motions of record warps, and follow any record eccentricity caused by an offset center hole - all without wreaking undue wear on the delicate grooves themselves. Except for one small problem - the groove is a moving target. It is cut in a spiral, requiring the tonearm to keep up with this path. It's a one-shot deal, in real time no less, without the benefit of error correction. And as if all that is not enough, the requirements also include adjustments for VTF, VTA, azimuth, and overhang.

The tonearm is not only the most active, but also the most influential component in a high-end system.