DAC Upgrade from Jolida JD100?

My budget Aune T1 DAC/amp seems to have lost its bottom end. I still have to swap out the cable but it's the same cable I had been using. Assuming the amp is boogered, I'm wondering about upping my headphone amp game. The bass is horrible. Tried two sets of headphones.
I hadn't been using the T1 tube DAC, so it prob wasn't the wisest purchase in the first place.
In any case, I'm wondering if getting a more recent DAC/amp and using the digital out of the JD100 will offer any improvement in the resolution? I'm not unhappy with the JD100 in general. Just considering all aspects of a new headphone amp.
I'm using Senn HD600 cans. The bass is OK with the JD100 headphone jack.
I believe I would need a newer DAC to handle hi res streaming. Heretofore I have not streamed hi res but it's something to consider. Would using a newer DAC offer any improvement to the sound of CDs? I realize the digital out of the Jolida bypasses the tubes
Budget around $300. That may suggest getting an amp only and sticking with the JD100's analogue output.
Thanks for any ideas and what might pair well with the HD600's.