After a distinguished 18-year career in audio circuit design, Dr Alex Cavalli shut down Cavalli Audio and retired as an industry heavyweight. Cavalli made it known he would rather stop short his famed run rather than sacrifice his reputation for quality, performance, and sensible prices. Recently, however, Cavalli has found the right partner in California-based Monoprice to restoke his fires and give headphone amplifier design another go, starting with the introduction of the Monolith by Monoprice Liquid Spark headphone amplifier. Cavalli Audio once planned a portable amplifier to be named the Liquid Spark, so this amp pays homage to a product that might have been. This is great news to those of us who lamented Cavall’s retirement, but even better news is that Monolith’s Spark will retail for the rock bottom price of £76. While some of you may have rolled your eyes on hearing this price (thinking good things must cost more), don’t sleep on this extremely small headphone amp as it really packs a punch and lives up to the reputation Cavalli so carefully crafted over the previous two decades.
The Liquid Spark uses a DC-coupled topology from the input to the output stage and is a fully discrete design. This approach eliminates the need for capacitors and op-amps in the signal path that might colour the overall sound. At the differential input stage the Liquid Spark uses laser-matched, low-noise audio JFETs instead of traditional bipolar transistors. JFETs are known to perform well in low-level applications, producing little noise while at the same time providing high input impedance. The output power stage employs high performance MOSFETs, which are ideal for designers looking to provide high power and very clean amplification within tight space constraints. The net result is a compact headphone amplifier that employs dual 18V filtered power supply rails that produces a convincing 1300mW RMS per channel into 50 ohms with very low distortion. With adjustable gain on the front panel, the Liquid Sparks exhibits a remarkable ability to produce a full sound that is crisp, quick, and sits quite comfortably in comparison with headphone amplifiers double or even triple its cost, as we will discuss shortly.