Recently, I got myself my first pair of "good" cans, the AKG K551s. I've been amazed by their sound through my friend's Fiio E10K, however, they don't sound nearly as good with my PC's onboard SupremeFX S1220A. I've asked around on Discord about DAC recommendations for under 50$. Some people recommended the FX Audio DAC-X3 or X-6, others recommended me the Sabaj D2. I'm wondering if these are any good. I'm also open to other recommendations in the same price range and offers on the European used market.