The Acurus amplifiers used a small, cheep, 10uF aluminum electrolytic capacitor as the input signal coupling capacitor. If you are handy with a soldering iron you can replace this 3 cent AL part with a polypropylene or polycarbonate capacitor of similar value. To keep the new capacitor small you could use a 5 uF, 50 Volt poly part.. The poly part will be 20 or more times larger than the AL part, so i may need to have the leads insulated as not to touch other parts. I think you will be very surprised at the improvement you will hear with this simple modification.
Regards,
jac122555