Same ol question, system recs

Got an email from a person willing to spend about $3-4K on total system, but wants to start by outfitting a small studio/office in his new home with 2 channel setup, no vinyl, SONOS, monitor speakers with clarity, 3d soundstaging and can play softly (50-60 dB) with clarity.

I promised him a few years ago, when he moved to a home from an apt., that I'd help. He's mid 30's in age and pretty savvy with tech.

Two little kids under 5? Married, with children, as they say.
Your friend will have little time to enjoy a $4K system with two kids under five. Those are the years when family is everything. A nice $1.5K system should be his target. Better to put the balance of the money in the kid's college funds.