Adding the Capacitor Between Pins 1 & 8 Increases GAIN, so it will also Increase Noise.
If you do use this Capacitor, Also put in the Bypass Capacitor from pin 7 to Ground
If you Don't need the Extra Gain, Don't use that Capacitor from pins 1 to 8.
You should also have a 100uf Capacitor Between Pins 6 and 4.
If your Using this with HEADPHONE, you should have a RESISTOR In SERIES with the Headphones to Reduce Power and Noise.
For 8 Ohm Headphones a 100 Ohm Resistor is good.
For 32 Ohm Headphones a 390 Ohm Resistor is good.