Best Music Streaming Hardware Options

I’m in the process of building my system around my Apogee Acoustics Duetta Signature Series II electrostatic speakers. I just bought a BAT VK-600 amp w/ BAT pack and will soon purchase a BAT preamp. Currently, I stream Spotify at their highest 320 kbps compressed mp3 format, but I know I’ll need to get to at least CD/SACD quality. Apogees are very unforgiving towards source material that is lacking. Looking for recommendations from fellow audiophiles in two areas...
1. What is the best way for me to tackle Hi-Res streaming (Tidal, etc) from my iPhone over WIFI/Bluetooth (not sure if this is a good option compared to a player that does the streaming), cd/maybe SACD playback/upconvert? An example I’m thinking of is an all-in-one player such as Sony produces (at least as of a year ago was around $2k new).
2. Any recommendations for a tight budget are ideal. I would be looking for a preowned unit. I realize this portion will probably end up being the weakest link in the chain since my budget is tight, but trying to minimize impact as much as possible while being able to continue my obsession of discovering new music constantly like I do currently with Spotify.
Thanks in advance!