Some of my favorite uses for my Grados - even my PS500s - are to plug them directly into my laptop or Kindle Fire. And many of us use one of the most inexpensive amps on the market - the Little Dot I+ - and have no desire at all to upgrade. That's one of the most attractive aspects of being a Grado fan...if you don't want to drop big money on an amp, you don't need to in order to get fantastic sound.
They are certainly a prize to play every time. I like saving them like they are a gift every time I listen to them