If possible have him audition some systems of the kind he wants in rooms of similar acoustics to choose the parts of the system that sound best to him. Gone are the days when anyone could save up and afford "the best" expensive such as McIntosh or Marantz which cost the most but unlike today do not cost as much as half a million dollars for "the best" most expensive that goes far beyond the point of diminishing returns of what people who are honest with themselves can hear rather than imagine through placebo effect. That one can build a system almost nobody could begin to afford sets us free to try out more approaches to putting together a system where "You get what you pay for," might not be true, e.g. speaker cables costing over $20,000 a pair.
What sounds "best" is not the same for any two people.
What sounds "best" is not the same for any two people.