I really like the RNHP Precision Headphone Amplifier. A very straightforward and minimalist design. It allows one to have three different types of inputs all available at the push of a button. It accommodates a very wide range of headphone impedances. The volume knob has a very smooth throw and it is easy to dial in just the right volume. But more importantly is the sound. Effortless and natural. Lows are solid and uncluttered. The transients come through cleanly and naturally. And the midrange is focused and right there in front of you. At times I forgot that I was even listening with headphones on, being swept away in the music. Well Done indeed!