The 535s are an excellent choice. But make him aware that they have a tendency to sound a bit dark, focusing more on mids and lows than highs, because they have 2 low/mid drivers and 1 high driver.
Depending on the source, they need some equalizing to sound right. For example on my iphone with treble boost, they sound amazing. On my shuffle (no eq possible), still good but not as good.
Then again it all depends where he's coming from. If he's coming from high end headphones/speakers, he might notice this, if he's coming from craptastic earphones, these will simply amaze him, period.