Get a schiit gungnir multibit. Get a blackcat digital bnc cable. The blackcat comes with a BNC to rca adaptor for the bluesound end. Then go xlr out of the Gungnir to your preamp. You’ll be blown away. If you want to spend more money get the schiit yggy DAC, it’s better but man the gungnir is rad and you’ll be happy. FYI I just did this and my system is pretty much the same as yours
Blackcat
https://www.blackcatcable.com/collections/digital-cables/products/silverstar-75-spdif-cable-universa...
schiit
https://www.schiit.com/products/gungnir
Blackcat
https://www.blackcatcable.com/collections/digital-cables/products/silverstar-75-spdif-cable-universa...
schiit
https://www.schiit.com/products/gungnir