HI ALL I'M FORWARDING THIS FROM SLUGGO....
THIS REALLY ENHANCES THE AUDIO..
Look at the circuit board and locate R220. It is a 220 ohm resistor located between TR23 and VR7. Notice that it is installed in a location marked D23 on the board. Remove this resistor and replace it with a 1N914 diode (observe polarity). Then locate C87. It is in front of VR6. Replace it with a 12uf/35v electrolytic cap. This will make the 458 AMC circuit the same as all of the other 858 rigs. Really opens up the audio^^ ab v c^^
THIS REALLY ENHANCES THE AUDIO..
Look at the circuit board and locate R220. It is a 220 ohm resistor located between TR23 and VR7. Notice that it is installed in a location marked D23 on the board. Remove this resistor and replace it with a 1N914 diode (observe polarity). Then locate C87. It is in front of VR6. Replace it with a 12uf/35v electrolytic cap. This will make the 458 AMC circuit the same as all of the other 858 rigs. Really opens up the audio^^ ab v c^^