SPL Phonitor One D - Audiophile Headphone Amplifier with Digital InThe Audiophile Headphone Amplifier with innovative Phonitor Matrix, 32 bit DA converter and outstanding sound quality. For us the sound is always in the foreground. When it sounds good, we like to listen. To get such a sound, you need experience and technical finesse. We have incorporated both into the Series One. The Preamplifier Stage Two Burr Brown OPA 2134 SoundPlus operational amplifiers provide the pre amplification. These are specially designed