The LM386 is Not simply an opamp.
It is a power amplifier in it's own right.

The quiescent current with a 12Vdc supply is in the milliwatts.
So that wont make you say ouch.
The power dissipation of the package is 500 milliwatts (1/2 watt).
Again, no need for a heatsink.

If the device got that hot, it is hooked up wrong.
Most probably it is now bad.

Good Luck!

Yeah, there is not too much if anything 'out there'.

Layout drawing?

Hmmph.

Yeah, that's a 'ground' buss.

Not too sure about the slave.

I would have to question where you purchased the TDA2030 ic's.

That ic is no longer in production.

LM1875 is.

Understand that the reason for the capacitor on the output is because the power supply is a single polarity.

Therefore the output will 'sit' at 1/2 of the supply voltage.
Which is Volts dc.

The cap is not needed on a dual supply because the output 'sits' at 0 Vdc.

HH MA150 schematic:

"How does a dc voltage burn out a voice coil"?

Heat.

Have you installed C3/ C9 (0.1 uf) & R4/ R10 (1 ohm)?

Good to keep in mind that the IC output potential is totally dependent on the power supply voltages into a load.

Within the limits defined in the datasheet.

https://www.tubesandmore.com/products/reverb-tank-accutronics-8db2c1b

If you replaced the original mosfet's, I'll buy them.

NPN: "Never Points iN"

I believe the proper term for the PNP letters is: Points In Perpetually".

Other than that, nice job.

Nice!