گروه مجستیک الکترونیک

I know I skipped R4. That is not a problem :-)
Distortion is less than 0.1% up to 100HZ and increases to about 1% at 20kHz.
I haven't been able to find anyone who sells a suitable T1. You can always use two 24V 5A units in series. If you are building two amps (for stereo), then I would suggest using an old microwave transformer and rewinding it. Follow the instructions in the 12V To 120V Inverter, execpt wind 26 turns, twist a loop (center tap) and wind 26 more turns. That should work out to around 50 volts. You may need to add or remove turns depending on your transformer.
Q1 and Q2 will require heatsinks.