Nice idea with the idle current control. Personally I would add a 1M resistor between the wiper of PR2 and - power supply. The reason for that is born out of experience with pots and how wipers can go open circuit. With the extra resistor the idle current would drop to '0'... a safety/longevity thing of mine.
Another thought about C1A and C1B. This way the caps can survive high voltages but normally there will be almost no voltage across them. Some tinkerers claim paralleling 2 caps (in this case 10uF/100V for instance) will get you a lower distortion.
Any reason why the bootstrap is behind the fuse ?
use your EARS to enjoy MUSIC .... NOT as an analyzer