Power Amplifiers

Burson Soloist Headphone Amplifier


Design and Setup of the Burson Soloist Headphone Amplifier

With the Soloist, Burson takes the "Less is More" philosophy to another level. They have reduced the component amount from 32 in the HA-160 down to 21. 21 individual components do the job that is normally done by a single integrated circuit such as the Texas Instruments NE5534 OpAmp which is made up of a whopping 53 components. An OpAmp is essentially a tiny mass-produced amp on a chip that takes the voltage difference from the input terminals and amplifies it via a single-ended output. There are many benefits to using OpAmps in a design, but first and foremost is cost and simplicity. You can get good performance out of a cheap OpAmp with little to no R&D costs. However, taking the quick and easy way out is often not the answer to better sound quality. Burson has spent many man-hours designing their Field Effect Transistor (FET) circuit for the Soloist in order to get the shortest (in terms of number of components) and cleanest path from source to output as possible. The benefits of spending the time and money on a discrete design reveal themselves in the sound quality produced by the Soloist. The fewer the components affecting the signal path results in higher fidelity and greater resolution of the source material.

The Soloist is essentially a solid aluminum box, albeit a beautiful one, with beveled edges and a brushed finish. A few tiny LEDs indicate power, input source and output level. The case is designed to act as a giant heat sink, dissipating heat away from the internal components without the need for ventilation or heat sink fins. During operation the unit never felt anything beyond warm to the touch. It has a nice heavy feel for its size, making you feel like you are getting something special for your dollar. On the front is the variable output stage selector that offers a low medium and high setting. For sensitive headphones or in-ear monitors, the lowest setting works great, but for headphones like the HiFiMAN HE6, stage 3 delivers the necessary output.

To increase fidelity, Burson employed a 24 stepped attenuator for volume control. The action on the volume knob was smooth while providing just the right amount of resistance and a satisfying "click". It is easily one of the nicest volume knobs I have come across. The only downside to this is that there is no remote control capability. Given I don't have a 20 foot cable on my headphones and usually sit right next to the amp, I would gladly go without a remote in favor of better sound quality. However, this does make its use as a pre-amp a bit more limited.

For connectivity, the Soloist has 3 gold-plated RCA inputs. You won't find any balanced inputs on this unit, but unless you are dealing with long cable runs, the benefits of balanced over unbalanced can be argued. The Soloist also has a set of pre-outs that enable it to be used as a pre-amp, a feature the HA-160 does not have.