Интегральные усилители — Cayin CS-55A

The CS-55A comes from Cayin as a two-channel valve integrated that pairs a push-pull power stage with a built-in USB DAC, an MM phono stage and a front headphone jack. The output stage switches between triode and ultralinear modes, and the amplifier ships with EL34 tubes while also accepting KT88, so buyers can choose a version or upgrade later. Construction is hand-wired point to point.

Key specs that matter

Four EL34 tubes run in Class AB1 push-pull, fed by two 12AU7 and two 12AX7 tubes in the preamplification stage. Output is 38 W per channel in ultralinear mode and 20 W per channel in triode mode, into loudspeaker taps switchable between 4 and 8 ohm. Frequency response spans 5 Hz to 48 kHz at -3 dB, THD is 1 percent at 1 kHz and signal-to-noise without weighting is 92 dB. Four input pairs are provided - one phono, one USB and two line inputs, with line sensitivity of 280 mV and input impedance of 100 kohm. Through USB 2.0 the internal DAC accepts audio up to 32 bit and 384 kHz. The chassis measures 360 x 334 x 180 mm and weighs 17 kg, and maximum power draw is 270 W.

Engineering and use context

Cayin describes the CS-55A as a compact all-in-one piece that brings digital, phono and line sources into a single tube amplifier. A bias meter on the top plate and external adjustment points let the owner set output tube bias without opening the case, which matters when switching between EL34 and KT88 or when fitting a fresh set. A soft-start circuit protects the transformers at power-on, and the front panel is fully anodised aluminium on a vented chassis. A remote control is supplied for volume and input selection. With four KT88 tubes fitted, ultralinear output rises to around 40 W per channel, a little above the EL34 rating.

Pairing

With a moderate output in either mode, the CS-55A suits reasonably sensitive loudspeakers, and choosing the 4 or 8 ohm tap follows the rated impedance of the connected speakers. A laptop or desktop computer plugs directly into the USB port, while any turntable using an MM pickup connects into the phono section without an external stage. Headphones can be used through the front jack for late listening sessions without disconnecting the speakers, and two line sources such as a CD player and a tuner remain wired in together.

Alternatives

The Cayin CS-150A is a larger tube integrated amplifier using KT150 output tubes, rated at 100 W per channel in ultralinear and 55 W in triode mode.