Determining peak to peak voltage of an NE5532 using an 8 ohm speaker
You shouldn't be using an 8-ohm load and expect anything realistically sensible from this and most other op-amps. It's not a power-amp it's an op-amp!! See below: -



What you see above is the front sheet of the data sheet where they try and say all the nice things they can about the device - note the bit in the red box - if it were better than this they'd have said so.