1 (Transformer+ Rectifier+ Resevoir) and 2 Regulator

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I want to separate and reduce the interaction between the two channels.

The leakage current of the BJT is small so there will be no interaction between pair (C15, C16) of the left channel and pair (C17, C18) of the right channel.
Is this idea real?
 

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I cannot see what the dark rectangles (connected to C13 and C14) are? Fuses?

Apart from that, your circuit will provide a first order isolation between the two channels.

Heavy transients on one channel may still affect the other channel when the voltages on C13/C14 dive importantly. That can be improved with separate C13/C14's and separate rectifier bridges.

You may also improve the voltage stability by replacing the zener diodes with TL431 and parallel capacitors.
 
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I cannot see what the dark rectangles (connected to C13 and C14) are? Fuses?

Apart from that, your circuit will provide a first order isolation between the two channels.

Heavy transients on one channel may still affect the other channel when the voltages on C13/C14 dive importantly. That can be improved with separate C13/C14's and separate rectifier bridges.

You may also improve the voltage stability by replacing the zener diodes with TL431 and parallel capacitors.
Thanks you very much, FauxFrench!
Yes, that is fuses.
Is there any "sound color" effect or instability when using voltage regulator IC like tl431 or lm317? I have no experience with them.
 
Traditional thinking wants the supply voltage for an audio amplifier to be as low impedance, "stiff", as possible at any frequency (in the audio band) such that charge is available whenever the amplifier needs it and in the amount needed by the amplifier.

The design you propose has got no regulation loop which is both good and bad for low impedance.
It is good because you have no regulation-loop that needs to respond to sudden changes in current consumption, but less good because the zener-diodes are not very low-impedance themselves. Some ripple on the storage capacitors will pass to the output.

TL431 is a shunt regulator that functionally replaces zener-diodes (also price-vise for DIY), can be adjusted to a large range of voltages with two resistors (and a decoupling capacitor) and has a much lower impedance than a zener-diode. However, the TL431 is only a part of a voltage stabilization circuit as the effective output current is low. It is no complete solution.

LM317 is a complete voltage regulator delivering currents up to 1.5Amp if not buffered. 1.5Amp is rarely enough for an audio power amplifier but it is very useful for pre-amplifier circuits, DAC's etc. LM317 is applicable for electronic circuits where the current consumption is rather constant because a constant load does not challenge the speed of the regulation circuit. If used for a power amplifier, even buffered, too much voltage swing on the output, caused by variations in consumption, may affect the amplifier sound negatively.
Statically the output voltage is (rather) constant, dynamically it may vary importantly.

For your power amplifier I would use the circuit you propose, eventually with replacement of the zener-diodes by TL431 (with resistors and decoupling capacitor) such that your voltage reference is much more low-impedance than with zener-diodes.

Admitted: I have got my drawers full of TL431 but haven't had time to try them myself.
 
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