Headphones — Warwick Acoustics Acoustics Aperio

The APERIO is an electrostatic headphone system from Warwick Acoustics, a British company based at Mira Technology Park in Nuneaton, Warwickshire. Headphone, amplifier and cable were designed together as one set, and the maker positions it as a reference studio monitor system. The launch price was GBP 20,000 or USD 24,000. The lineup covers a standard silver edition, a black edition limited to 50 units and a gold version hand-finished in 24-karat gold.

Key specs that matter

Each driver is a Balanced-Drive High Precision Electrostatic Laminate, or BD-HPEL, a symmetrically driven development of the earlier HPEL transducer with twice its excursion capability. Diaphragms are multilayer, with 7 micron BOPP outer layers around an inner layer of 24-karat gold, and effective driver area is 3,570 mm2. Frequency response is quoted as 10 Hz to 60 kHz and THD as below 0.001%. The headphone weighs 405 g without its cable. The amplifier uses a balanced, discrete MOSFET, high-bias, single-ended Class A output stage with eight discrete 1000 V MOSFETs per channel, delivers 15 W per channel and supplies a bias voltage of 1800 VDC. Its chassis measures 68 x 413 x 351 mm and weighs 7.4 kg without the power supply.

Engineering and use context

The ear cups and other major parts are made of injected magnesium, which weighs about 33% less than aluminium and damps vibration better than aluminium and most polymers. Warwick states that low bass depends on a small sealed air volume between transducer and head, so the design is shaped to stop air leaking out. Cushions are covered in top-grain Cabretta leather. The 2 m cable is silver-plated OFHC copper with Kevlar reinforcement and low capacitance, ending in 4-pin self-latching plugs. Inside the amplifier, dual 32-bit eight-channel DACs work in dual mono and accept PCM from 16 to 32 bit up to 384 kHz, plus DSD up to 256 fs as DoP or native. Each channel's DAC sits in its own EMI-shielded chamber, and converter SNR is 131 dB. Clock jitter is given as 82 fs RMS at 100 MHz, with a noise floor of -168 dBc/Hz. Volume uses a laser-trimmed differential analogue attenuator for analogue and DSD signals and a 64-bit DSP attenuator for PCM.

Pairing

As the amplifier combines energiser, preamplifier and DAC, a digital source can connect over USB 2.0 Type B, Ethernet, AES3 on XLR or S/PDIF coaxial on RCA. Analogue sources use balanced XLR or unbalanced RCA inputs. Analogue inputs have high and low gain switches. Balanced XLR and unbalanced RCA line outputs mean the amplifier can also serve as a preamplifier for power amplifiers or active monitors.

Alternatives

The Warwick Acoustics BRAVURA is another electrostatic headphone system from the same maker.