Pier Audio MS-680SE

The MS-680SE from Pier Audio is a hybrid stereo integrated amplifier, combining a valve section with bipolar power transistors. It stands out through a design intended both for pure two-channel audio listening and for complementing an existing audio-video system thanks to a dedicated pre-out input.

Its power supply relies on a 750VA transformer wound in the traditional manner, using high-quality copper and Z11 steel laminations imported from Japan. The power stage employs 4 pairs of Toshiba bipolar transistors, while the valve section uses 4 valves (2x 12AU7 and 2x 12AT7) mounted in an SRPP configuration. The power supply and filtering capacitors are of Japanese origin (Rubycon/Nichicon), complemented by French polypropylene capacitors (SCR).

A distinctive feature of this model is its full by-pass: the signal systematically passes through the preamp stage and the 4 valves, including on the pre-out input. This input offers a sensitivity of 500 mV, compared with the usual 240 mV on standard RCA inputs, allowing better use of the pre-out output of a mainstream audio-video amplifier and correctly driving the main speakers of an AV system for more consistent stereo listening.

Volume adjustment is via a motorised ALPS potentiometer, designed to temper the unit's natural dynamics. The MS-680SE also incorporates a USB input based on a Texas PCM2706 chip, to be regarded as a supplementary DAC: it plays WAV and WMA files at 16-bit/44.1 kHz, without FLAC support.

This model is aimed at enthusiasts wishing to combine the perceived qualities of valves (depth, tonal liveliness) with the rigour and power of a transistor stage, in a classic stereo configuration or as a complement to an existing audio-video installation.