Upgrade advice needed, where?s my weak link?

Hi, I currently have an OPPO 205 feeding into a Cayin A 88T MK 2 tube amp with Bower & Wilkins 683 S2 speakers. Mostly listening to Jazz, acoustic, female vocals but also some 70?s prog. Room is 40 square meters and sonically well damped. Speakers seem to be an obvious choice to upgrade but to what. I am also thinking that selling the OPPO and investing in a streamer/dac to connect to Tidal and Spotify might bring greater improvements. I am hoping for a bigger sound stage with more detail but not fatiguing.
What are my options?
Thank you