Grado RS2 Headphones & Grado Amp

Working together, do these need a break-in period for optimum sound? If so, how long?

Give it 100 hours or so at a slightly higher volume than you would normally listen at. The RS-2's are kind of 'bright' out of the box but will settle down a little. I've never owned them myself, but have 5 other pairs of Grados and they all use drivers with similar construction and materials. Don't expect any miracles, but breakin should tame them a bit. The amp might need a little more time, but it's pretty neutral to begin with, so again, you can expect slight improvements but nothing dramatic.