"We love that big piano."
Translation:Nos encanta aquel piano grande.
Eso/esa use when the object is near you where you can see it and aquel/aquella when the object is away.
Nos "encatamos" aquel piano grande. sounds bad in spanish and is wrong because "encantamos" it mean enchantment in spanish.
aquel (male, that even farther away), aquella (female ,that even farther away)