The NJM5532/NE5532 will also sub nicely for the NJM5534D. The only significant difference between them is that the NJM5534 has a Slew-Rate of 13V/µs with a BJT (low impedance) input while the NJM5532 has a Slew-Rate of 9V/µs with a BJT (low impedance) input. The difference is not retable by the human ear. Mouser has them.