[martin.m]

Just spotted this thread. I have a Leak Delta 30 and am investigating a similar problem. My RH channel is quieter than the Left and slightly lacking in bass. If you have a CD player try connecting it to the tape replay input then listen with the front panel "Replay" button pressed in. This bypasses the preamp and tone control circuitry by feeding the signal directly to the Leak's power amp circuits. If the performance is restored, then the problem lies in the preamp circuits. The Delta 30 is over 45 years old now and some of the electrolytic capacitors are likely to have deteriorated.