Analyzing Balanced versus Unbalanced Amplifiers--Difference in sonic quality?

I wanted to see what the new Technics high-end products touting new technology were all about. What Technics did here was create an LAPC circuit that tests and monitors speaker output via a computer chip versus balanced sound. According to Audio Advice, this circuit does more for the sound than a balanced presentation.

In high end audio implementation is everything, the design, the exact components used (manufacturer and type of resistors, capacitors… etc). Playing with the signal digitally is virtually always a bad thing. Really good equipment doesn’t touch the analog signal. While digital manipulation is getting better… good sound virtually always comes from applying the “short wire” principle of keep things simple and short, no tone controls, no equalizers. So the balanced vs unbalanced comparison  depends on who is designing and implementing it. Who and how  makes a much bigger difference than single versus balanced. It does make sense to talk about this when all other components and layout exactly the same… but that doesn’t really happen in the real world of audio products.

Ghdprentice:

Well stated. I reference the recent Stereophile (December, 2021) issue reviewing the Technics RU-1000 all digital amplifier and it truly is unique. Obviously, every electronic component will have a "sonic signature" regardless of its 'flat' delivery. When I hear or read audiophiles talking about a flat uncolored sound, I say 'hogwash'. Even mega six-figure components create a sonic coloration of sound even if in our collective humanity subjectively hear no coloration. 

To me it analogous to a silent nuclear sub: their silence through the water still creates a sonic signature unique to that submarine; the sound signature will even differ from identical amplifiers.

My point about balanced cabling is that most Class A/B amps have balanced wiring internally due to their construction. This Technics is not a D-Class amp per se because it doesn't convert analogue signals at their entry. Thus, there was no need to balance the internal wiring for that short distance within the unit itself.

Anyway, enjoyed your post as spot on.

My point about balanced cabling is that most Class A/B amps have balanced wiring internally due to their construction. This Technics is not a D-Class amp per se because it doesn't convert analogue signals at their entry. Thus, there was no need to balance the internal wiring for that short distance within the unit itself.

This statement is false. Class A/AB amps do not always have balanced wiring internally. From the Technics website:

However, conventional digital amplifiers are connected to speakers through a low-pass filter at the output stage, so they are even more strongly affected by the speaker impedance characteristics. Also, although the amplitude characteristics of conventional amplifiers due to negative feedback were improved, the phase characteristics could not be enhanced. We thus developed a speaker impedance adaptive optimisation algorithm that performs correction to the ideal impulse response through digital signal processing by measuring the frequency amplitude-phase characteristics of the amplifier with the speakers connected. This new technique enables flattening the frequency characteristics of amplitude and phase, which had previously not been achieved by amplifiers, as well as delivering a sound with rich spatial expression.

There's stuff here that isn't correct either. So I can see it being easy to get misconceptions! We'll start with the first sentence, which is false. A class D amp can act as a nearly perfect voltage source, limited only by heatsinks, current in the power supply and how much current the output section can handle. What happens with different load impedances is that the Q of the filter is reduced as impedance is reduced. This does not affect the amplifier output power though.

The second sentence is also false. It appears that they are trying to get around Bruno Putzey's patents if I had to guess; at any rate phase relationships can be perfectly maintained right up to 20KHz if the class D amp is designed properly. Not sure what 'enhanced phase' might mean; that might be a reference to their servo system between the amp, speaker and remote. But that can operate independently of the amplifier used.

If the speaker is designed properly there will be no need for phase correction.

I agree that everything has a sonic signature; with any amplifier its 'sonic signature' is actually its distortion signature; how the lower harmonics relate to the higher orders and how much IMD is present.

Finally, class D amps may well have balanced internal wiring. This often takes the form of traces on the module (the module being the circuit board on which the class D power amp resides). This is often done to reduce very high frequency noise, which otherwise might interfere with radios and the like.