I would definitely start with upgrading your source.
I started out feeding my dac with an iPhone, and it was terrible. I bought an Auralic Aries, and it was a night and day difference. My streaming (Tidal masters) SQ now beats the pants off red book CD audio fed into the same dac. Auralic’s Lightning DS app is incredibly easy to use. I love this unit.
There’s an Aries for sale on eBay right now for $599 which is a great deal.
Here’s a couple reviews of the Aries