inside1 Published December 16, 2012 - size: 700 × 739 in How to build the Apheared 47 Headphone Amplifier for Grado Headphones ← Previous Next → The guts of the amp. Note that I managed to shove a 1/4″ jack into the case. Many people use a 1/8″ jack to save space, but I wanted the grados plug in directly without an adapter. Read More...