upgrade advice

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
Ok, I'll bite.

Great speakers, OK amp/dac, crappy source.

Personally I'd invest in a few good power cables, that will tighten up the bottom end and open up the sound stage.  Next I'd look into upgrading the bluesound. 

Yes, I agree. You have a very nice integrated.  If it's one thing I have learned through R&D and experimentation is that your source is extremely important.  If you don't have the sound quality from the start, there is no way you are going to get it back with cables/power cord/etc.  Better cables and power cords can help, but they cannot fix a bad device.  My vote would be to look into getting a very good DAC.  Maybe you can give us your budget on how much you're willing to spend right now.  Some ideas are offerings from Marantz, or maybe a Gustard X20 (Maybe a Schitt).
thank you 
do you mean that i have to use better DAC than the HEGEL internal ?
or to buy high end streamer and coonnect it to the HEGEL digital input?
my budget is up to $2000.