48 x NE5532 AMP

Yeah. Can be fun. If I would know that the layout is perfect, I might give it a try also.
Tempting to use OPA1656 or similar but the layout might not be up for it.
I'd use a unity gain stable opamp and use it as buffer/low-gain-amp for compression drivers.
 
I think 12WPC is wishful thinking from this - at least without a heat plate or something.
Looks as if they just parallel the lot. 24 for each channel.
If that is the case, you could theoretically make a bridge amp from both halves but will need an inverter in front to drive the second half and eventually modify the board a little.
Using OPA1656 or the cheaper OPA1692 you could get quite a high max. current figure but I always doubt if its lots of work to make them play that well together. Definitely easier and cheaper to go out and buy a composite amp from Neurochrome or so.
If I wasn´t drowning in projects that want to be finished I´d make a PCB for maybe 5-8 OPA1656 each channel for some high-sensitivity drivers.

Regarding the heatplate: there is a plethora of thermal pads nowadays to be had. Used them at work in thicknesses up to couple of [mm] and then placing that on an aluminium plate.
 
I think 12WPC is wishful thinking
I didn't scratch-up 5532 specs; for the similar-market OPA1656's specs I figured 11.78 Watts which is close-enough.

The half-Watt dissipation per chip may be tolerable in a DIP-8 (the '1656 does not come in a serious package); may not survive 48 hours at full sine output, but will be fine with lightly clipped speech/music.

IAC, someone else can solder this beast up.