And in addition to the HPA-23RM's current-source output, Chae has designed a completely separate circuit and output that functions as the kind of voltage source found in 99 per cent of other amps, intended for use with your
Focals, Fostexs and earphones.
In this portable Enleum are therefore two entirely different headphone outputs that allow you to mix and match between what sounds best with your transducers, and act as an empowerer for all your flagship sources.
3.5mm or RCA line-in from any of
Cayin Audio's N7 and HiBy Music's RS6 or RS8, for fireworks at your desktop or on your travels.
But if you are familiar with Enleum and Bakoon, you'll immediately gravitate toward its specialised trademark: the current-source output on 1/4". While there may be temptations to draw quick and easy comparisons to current-mode amplification found in products like
Mass-Kobo and Questyle Audio, Enleum's current-source amplification is entirely unique and mutually contradictory.
Working in a way that keeps output current levels constant at all times, even as impedance and voltage fluctuate, the HPA-23RM aims to address a perennial problem – that headphones and earphones induce distortion in amplifiers because they are not simple resistive loads, but rather have complex, frequency-dependent, inductive and capacitive components.
However, with the HPA-23RM aiming to eliminate distortion by driving headphones as a constant current source, you experience much greater linearity, hearing an output that faithfully reproduces what was received at the source: the input. Reduction in the effects of backward electromotive force from headphone drivers results in a cleaner sound.
With greater linearity and a more accurate final product, negative feedback, typically employed to correct glaring errors, can be eliminated in the HPA-23RM. Enleum's circuit transmits the signal faster and can be kept simpler with far less transient intermodulation distortion arising from feedback.
Single-ended operation emphasises even-order harmonics over odd ones, granting a natural portrayal of music that never once sounds artificial.
Enleum's JET2 sliding bias scheme intelligently monitors the operating conditions of the discrete devices that make up HPA-23RM's circuit/s, ensuring that transistors operate linearly biased against their current sources in single-ended operation, without generating excessive heat from full Class A. This is a thoughtful addition for a portable product.
Listeners can enjoy these innovations with both the current-source and 3.5mm voltage-source outputs on the HPA-23RM. If you aren't into art nouveau and aren't ready to embrace Enleum's current-source output, stick with the conventional voltage-source output that has defined gain amplifiers for nearly all of history.
Your ears would certainly benefit from experimenting with either circuit, each completely separate from the other. Some of your gear would certainly thank you, especially those that gravitate towards the low output impedance typical of a voltage source, like Focal's
Utopia and IEMs.
These transducers also particularly crave a low noise floor. HPA-23RM's precise relay-based discrete resistor volume control provides just that – but not in the way you think.
Rather than attenuating signal levels, it's a variable gain volume control that leaves the fragile input signal untouched. Instead, it changes the total amount of gain that's applied to the signal, with only the necessary amount used and never incurring the consequence of detrimental noise from an excess.
Variable gain is possible only because HPA-23RM is a zero-feedback design. Enleum's volume control is ideal for preserving the signal-to-noise ratio and the true dynamic range of your music. And a fully-regulated 18650 battery power supply, operating at 1.2MHz, similarly ensures a quiet performance.
HPA-23RM is thus a tour de force that demonstrates how mature Enleum has become, offering users abundant choices between two completely different circuits in one chassis – each on par with the other in terms of quality, with only synergy defining your final choice.
Look up all of Enleum's gear
here, or view our other amplifiers here.
Amp Current-source bipolar / voltage-source MOSFET
Output power <1,000 mW current-source / <500mW voltage-source