I stayed in Juan Carlos' studio for a bit less than a month while moving to Madrid, he's been of great help with directions around the city, recommendations on places where to eat, etc.
The studio is in the Lavapies barrio, an area that gets really alive during night time, although due to the pandemic we weren't able to live it as much as we could have in other times. Right next to a 24h supermarket and the underground station, really close to the center of the city as well.
I can only recommend Juan Carlos!