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I've just checked Malachite schematic I have - no R21/100K. I've also compared Sanguine and Malachite build docs. There is one resistor missing on the Malachite pcb layout drawing (upper right corner). But.. R21 is present on the Malachite pcb image here. Aaand.. if you take a look at the post...
You need a PSU that can give you 1A to 2.5A, depending on the type of the power amp. Because of this you cannot use any of the poplular charge pumps we usually use. Traditional power supply would be big and heavy (transformer). I'd search for good quality switched power supply.
JBoss - you can use SMD version of the 5457 - MMBF5457. You can also use 5458 - gain of the stage with 5458 will be slightly lower than with 5457. To compensate for this you can increase value of the drain resistor from 22k to 24k. But you can also leave the original value.
You can start with biasing each transistor @ 4.5V (measure voltage on a drain of the transistor). Then experiment :) . Make slight adjustments - for example go up and down 1V wiht 0.2V steps and find the best setting for you.
You mean replacing 250mH with 250uH? According to the ltspice simulation 250uH inductor equals to no inductor.
From left ro right - 500mH, 250mH, 100mH, 50mH, and three overlapping traces - 1mH, 250uH, inductor shorted.