After years of relying on other equipment to drive Grado headphones, you can now listen and enjoy headphones through our new Grado Reference Headphone Amp, the Ra1. Designed for state-of-the-art performance and specifically to play Grados, the new RA1 will allow you to hear your headphones like never before. This new amp is machined from a solid block of mahogany and measures 5" wide, 5 1/2" deep and 1 1/2" tall and weighs in at 12 oz. The RA1 is available in an AC version or can be powered by two 9-Volt batteries that will drive the amp for 40 to 50 hours of listening pleasure. And the sound? Just like all Grados: warm, smooth, full-bodied, non-fatiguing and rich. Hook it up to any line source (portable or in-home) and drive your Grado headphones to their full potential. The Grado Labs RA1 headphone amp was designed specifically to drive Grado headphones and it does that quite decently indeed. It's recommended for use with fairly efficient (low impedance) headphones like the 32-Ohm Grado Labs headphone line. This is the battery-powered amp unit. The 'AC-power' Grado RA1 (Ac) version is also available. The RA1 design is small and fairly light for portable use, although that trad Grado wood-block design makes it somewhat bulky for easy travel and mobile listening on the fly. It's a very simple yet effective & the front panel sports a volume control, an on/off LED light, and a full-size 1/4" headphone jack. The rear of the amp provides an on/off switch and one pair of left/right RCA inputs. The battery compartment holds two 9V batteries, and is easily accessible via a metal plate with two screws located on the bottom of the amp. One bummer: the battery-powered Ra-1 does not operate with a wall wart/AC adapter.