Within your budget, I feel the simplest solution is :
- Marantz PM6007 @ Rs 35K
- Mi Box 4K @ Rs 4k
Total Rs 39K
Connect the Mi Box to the Marantz via the optical out, connect the Mi Box to WiFi , and you are done.
Spotify Connect, chromecast, all will work perfectly.
Is there optical out on mi box 4k? All i see on their website is 3.5mm Jack.