Diego, his wife, and his father Julio are absolutely fantastic hosts. Diego gave us a warm welcome, informing us that if we needed anything, he would help. Further, Julio provided us with stories and great recommendations around town.
The location of the stay is perfect - we found ourselves within walking distance of everything (the Prado and El Retiro may be a little far for some, but a lovely walk regardless)!
If I ever find myself in Madrid again, I will absolutely be returning to this stay.