Усилители для наушников — Lehmann Audio Linear USB II

The Linear USB II from the German maker Lehmannaudio adds a USB digital to analogue converter to the analogue circuit of the Linear family, and it belongs to the home category of the Lehmann catalogue. It works as a desktop source for a computer and as a line-level headphone amplifier, with a US price of USD 1,999.

Key specs that matter

Output power reaches 400 mW into 60 ohm and 200 mW into 300 ohm per channel. Gain can be set to 0, 10, 18 or 20 dB with DIP switches. THD is below 0.001% at 6 mW into 300 ohm, noise sits more than 100 dB below full output with gain at 0 dB, and channel separation exceeds 80 dB. Frequency response spans 10 Hz to 35 kHz within 1 dB. The headphone sockets have an output impedance of 5 ohm and the line output 50 ohm, while the analogue input presents 47 kohm. The case measures 110 x 280 x 44 mm and weighs 1.5 kg.

Engineering and use context

An ESS Sabre K2M converter chip accepts PCM up to 32 bit and 384 kHz over a USB type B input, with DSD carried as DoP, and the converter delivers a maximum of 1.8 V RMS. An RCA analogue input sits next to the USB port, so a separate line source can share the amplifier. The rear also carries two pairs of gold-plated RCA line outputs, one switched with the volume control and one fixed, which lets the unit feed a power amplifier and a recorder or second system at the same time. Two Neutrik headphone jacks with gold-plated contacts are on the front, and the circuit uses the low-impedance copper board technology of the maker. The faceplate can be ordered in silver or black, and the compact 110 mm width lets the unit sit beside a monitor or laptop on a desk.

Pairing

A laptop or streaming computer connected over USB is enough to form a complete headphone system, and the variable line output makes it possible to drive active monitors or a stereo power amplifier directly. The gain settings cover everything from sensitive in-ear models, where the lowest gain position keeps the volume range usable, to high-impedance dynamic headphones, and two listeners can use the dual outputs together. When the unit is not in use for headphones, the fixed line output can keep feeding a recorder or second amplifier at full level regardless of the volume setting, while the switched output follows the front knob.

Alternatives

A DAC-free option from Lehmannaudio is the Linear II Pro studio amplifier, fitted with balanced Neutrik combo inputs and a 50 mm tall case.