No there isn't.
It needs inputs. If there are more than one, it needs an input selector.
It needs a volume control (not necessarily a physical one, one on a wireless smartphone app is an alternative.)
It needs an amplifier with speaker terminals
All the rest: headphone amp and plug socket, DAC, digital inputs, preamplifier gain section, controls for bass, treble and balance, selectors for different speaker pairs, subwoofer outputs, phono preamp, tape input and output, streamer boards, wireless transmitters to wireslee speakers, Bluetooth are all optional.