The following parts have been replaced:

- Electrolytic Capacitors have been replaced by high quality ones from well known brands

- All transistors have been replaced by low noise replacements

- Replaced a couple of resistors to reduce the gain so the unit is more suitable for newer devices

Board can look different than the listed picture as Quad sometimes used different looking parts on revision 3 and 4 boards. 

All boards have been tested by ear and with a scope to ensure that they are fully operational.