Look and read about the Allo Kali and the Hifiberry DAC+ pro which both have abilities to improve the RPi’s I2S clock signal which is important in how everything sounds in the end.
Also the Mamboberry has a lot of good reviews.
Finally, if you are looking into improvements, also take a look at how you power your streamer (think SBooster or other better power supplies than stock).
At the end, try and listen to alternatives to find your personal improved sound. YMMV