"The foundation of the HD Audio Opamp is a sophisticated Voltage Differential Amplification network."
Hmm... are there any op-amp with single-ended input? But it wouldn't be called an op-amp by definition.
"without rigid component matching, it would be easy for sonic imbalance to occur."
Let me check Farnell - the most common value of tolerance for resistors is... 1%, at 18574 items.
Maths time - how much is a difference of 1% in decibels?
i.e. what is the difference in decibels between a 1.01V signal and a 1.00V signal?
Correct! The answer is 0.086dB.
Go and hear that.