Parasound's Hint 6's new volume control provides huge sonic advances?

A volume control is a voltage divider. To achieve this the sensitive signal must pass through either resistors or transformer windings. There will be two voltage dividers, one for each channel. It’s essential that these dividers achieve the same result for each channel, as the volume is varied, in order to maintain a good centred image. It is also essential that they don’t affect the signal in any way as they’re varied, ie, the sound quality is exactly the same at really low levels as at higher levels.
 If the voltage divider is a potentiometer, then the material the resistive track is made from will effect the sound quality and the two resistive tracks must match exactly. If the divider is switched resistors, this gives the opportunity to use more precise channel matching, and ‘better sounding’ resistors. If the divider is windings on a transformer, you avoid resistors all together and can achieve perfect channel matching. The only other approach, and the best I’ve yet heard, is how Lyngdorf do it, which is not to vary the music signal itself, but to vary the PSU voltage to the output driver stage.
In order of sound quality from poor to best, its Potentiometer, Switched attenuators, transformer and finally Lyngdorf’s approach.
As the volume control quality improves, the sound stage becomes more stable, sound quality more consistent from low volume to high and transparency improves.

@richtruss Thanks for that explanation -- belongs in a textbook, it's so clear! I see the kind of difference better now, and over the other range of methods. If I were comparing other options and price ranges of integrateds, I might look to see how they differed in this regard, though I still don't know the degree to which improvements in volume control  (from model to model) would matter (to my ears, at least) compared to other design elements contributing to the sound. 

Interesting thread, I do volume control completely in the digital domain which of these methods covers that?

Ha! Got me 🙂 None, I was just referring to analogue, but Digital would of course avoid these issues, like the Lyngdorf approach, as it’s not hitting on the analogue signal.

1. Whether the Para 6 is better largely depends on the connected equipment. It may track better, but that's only a small part of the perceived sound.
2. 'Better sounding resistors'? In whose estimation and in what context? Higher precision will improve tracking. SMD reduces inductance. Metal film has negative while Carbon film has positive temperature coefficient. How will those changes react with the associated equipment?
   
3. Transformer taps change impedance which may affect sonics due to LCR filter values.
4. Varying PSU voltage introduces its own artifacts
5. Digital audio math becomes progressively worse as signal level drops and attenuation increases.

There is no free lunch.