upgrade advice


Hi
i bought the Hegel h160 integrated amplifier with pair of Spendor D7 loudspeakers.
the source is bluesound node 2 .
speakers cables are VOVOX vocalis. all other cables are regular.
i want to upgrade my sound and wonder what would be the best way to start.
to change my power cable,my digital cable,speakers cable or buy a better external DAC  than the hegel internal.
thaks for your advice
yansad