HEGEL H80 DAC upgrade recommendation 2018

Hello,
I just purchased a Hegel H80 and am new to the "audiophile" world. I am however enjoying my new setup. I’m wondering if anyone with an H80 has upgraded their system to a new DAC where you’ve noticed a significant difference from using the onboard DAC (all things being equal, same speaker, wires, etc.). Please note that I got the amp for $650 so at the time of this post, I want to find a DAC that makes an audible difference but isn’t significantly more in cost than the amp unless the quality is wildly discernable on this amp with the DAC you recommend.. Open to better but older DACs that can be had for less used or any of the Shiit, ifi, SMSL, etc. DACs then please let me know. I really appreciate your first hand experience with the H80 and any recommendation you have to offer. Finally, l’d love to know if you found any difference between using the line or balanced inputs with your DAC. Thanks.

Hooman