I wouldn’t expect an old cd player in the league of the jolida to beat a modern cd transport like the Jays CDT2MkIII. Better power supplies, better clock…it’s in a different category.
You really have few options to improve your sound, IMO -
1. Try XLR interconnects from DAC to Hegel (cheapest option). Get out of your full cable loom mindset and try what works best
2. Upgrade DAC - much bigger yield than cable upgrade but also more costly
As far as DACs are concerned, you have a lot of options but I would say look for $5,000 + retail price DACs. Figure out the sound signature you want and you can narrow down the list of candidates