Hi,
1) you think there is something wrong. And I guess the schematics are from reliable sources. If so, then the issue lies in your wiring.
Thus it´s important to show us your wiring.
2) you say you can hear a hum. This most often comes from mains frequency. Your schematic shows a battery as power supply. But I guess oyu are using an AC/DC adaper, am I right? If so, then this probably is the cause of the hum. Try a battery to verify.
If the battery
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In either case: for Audio circuits proper wiring, especially a proper GROUND-concept is important.
This is not a simple task, especially when one expect some decent quality.
Regarding quality the almost 50 years old LM386 isn´t the best choice.
Klaus