HPA4 and AHB2 Review - Fidelity Online

"The benchmark combination offers a full range of equipment that can hardly be topped, leaves nothing to be desired in terms of sound, and meets professional requirements without any ifs or buts."

HPA4

"Two very different headphones were used to check the capabilities of the corresponding output on the benchmark pre: my ultra-light, electrically undemanding Grado SR80, which regularly has a sound that is far too good for the price range, and a HIFIMan Sundara, an officially high-end magnetostat."

"The benchmark shows what it's capable of..."

"The HPA4 has the HIFIMan one hundred percent under control, eliciting neutral timbres, tons of spatial information and crisp dynamics."

"My current favorite record, Origami Harvest by the American jazz trumpeter Ambrose Akinmusire, whose mix of hard rap, classic string quartet and eruptive jazz combo is not for beginners, flows so neatly into the ear that it is a pleasure."

"If the design goal was to construct a reinforcing piece of wire, then it has been achieved."

"Operation via the touchscreen and the level control that switches a record-breaking resistor network is fun and at the same time gives you a pleasant studio feeling - at least if you mean the same thing as I do by “studio”, namely precision, control, perfect reproducibility and absolute reliability."

AHB2

"When the decision was made one day to bring the first regular power amplifier onto the market, the requirements were clear: What was needed was maximum energy efficiency, low distortion at the limit of the measurable, and no sound of its own."

"It is indeed an achromatic enhancer, pure as a spring wind. A spring wind with power."

"The AHB2 is a class H amplifier in which a switched-mode power supply supplies a class AB circuit and, thanks to the variable voltage supply, reduces power consumption enormously."

"The basis of the circuit is a combination of negative feedback with the extremely efficient, but far seldom used principle of interference suppression by means of feedforward error correction. In German this is called “Mitkopplung” and means - to put it very briefly - the supply of the phase-inverted distortion component to the output signal."

"It amplifies the signal supplied and otherwise stays out of everything."

"I connected everything the household had to offer in terms of speakers - Spendor S3 / 5, Ayon Seagull / c, Quad ESL57. It goes without saying that the American coped with the dynamic boxes with ease. But even the quads, which have some meanness on the part of their impedance, did not pose a challenge for the amp."

"In short, it is the best tool and therefore the first choice for everyone who wants to drive difficult boxes to maximum performance without going into personal bankruptcy."

- Michael Vrzal, Fidelity Online

Read the full review here →