The schematic should be as simple as a good 340 watt solid state amp can be.
The output stage works mainly in class AB and in fact not much different to a class B amp where there is no idle current at all. With no source follower or global NFB the THD of a pair of mosfets in complementary pair might be 10% at 250 watts into 8 ohms. The 27dB of local NFB used in the source follower connection reduces
this to less than 1%. There is about 50dB of global NFB which means a total of 77dB is operative.
Most of the crossover distortion artifacts are reduced by the local output stage NFB.
The 53dB of global FB reduces the 4% open loop THD by 53dB, or by a factor of 0.00223, so 4% becomes 0.0089%, or just under 0.01%.
The THD is approximately proportional to the output voltage, and at 4.5Vrms output which is 2.5Watts/8ohms, THD < 0.001%, and rather difficult to measure easily.
Such low THD is typical of many solid state amplifiers.

However, excellent THD, IMD and TID measurements do not always tell the whole story about how an amplifier will or will not alter the sound signals than pass through it.

Tube amps with ten times the THD,sometimes can sound better.
With the class AB 340W amp as it is, any type of load can be connected and an 8 uH inductance in parallel with 8 ohms protects the output stage from over heating if it ever had 5uF connected and the output signal had a high level signal above 20kHz.
5uF is a difficult load, but there may be some electrostatics, possibly made by "Martin Logan", which present such an awkward load to an amp, but usually all awkward loads do have a series resistance in their equivalent impedance
characteristic so that the worst of phase shifts and peak currents at above 10kHz will not bother the amplifier.
This design would become overheated with a load of 1 ohm and worked hard but then the fuses in rails or at the output ( not shown ) would blow. The amp is meant to be used with loads above 4 ohm, but will tolerate normal home use with loads
down to 2 ohms where power is unlikely to average more than 5 Watts per channel, ever.
The only way to increase low impedance speaker load power handling is to use more of the same output devices or use devices with higher ratings and more of them on a bigger heatsink. Exicon flat pack mosfets rated for 16 amps each, which would allow 40Vrms into 2 ohms giving 800 Watts.
I have never ever needed more than 50 watts for hi-fi at home.

Amplifier specifications:
Full power bandwith 8ohms,3 Hz - 80Khz
300mA idle current rail to rail in 8 output mosfets
Open loop gain at 200Hz = 20 000
Closed loop gain = 47
Global NFB = 52,6dB
THD 1Khz ..... <0,01% at 340 watts
               <0,0015% at 40 watts
               <0,0005% at 4 watts
However, excellent THD, IMD and TID measurements do not always tell the whole story about how an amplifier will or will not alter the sound signals than pass through it.
People have told me why my tube amps and mosfet amps both sound very well.
One reason is that they run warm but not stinking hot, they have some class A working rather than none, and were designed and made by the same man, with an uncompromising attitude about how things should work.