Phonostages — Pass Labs XS Phono

The Xs Phono is a two-chassis phono preamplifier from Pass Labs of California, the company founded by Nelson Pass. It replaced the XP-25 and was first offered in the United States for USD 45,000. Pass describes it as dual mono from the power inlet through to the outputs, with the left and right channels kept apart at every stage.

Key specs that matter

Three cartridge inputs are provided, and each is a complete stereo phono stage of its own, so no switch or relay sits in the signal path when changing between turntables or tonearms. Gain can be set to 56, 66 or 76 dB. Resistive loading has 11 steps from 30 ohm to 47k ohm, and capacitive loading has six steps from 100 pF to 750 pF. RIAA accuracy is quoted as plus or minus 0.1 dB from 20 Hz to 20 kHz, and response reaches below 5 Hz when the filter is off. Both output sets, XLR and RCA, are live together. Each chassis measures 483 mm wide, 356 mm deep and 159 mm high, and the pair weighs about 36 kg.

Engineering and use context

The audio chassis holds 13 circuit boards and around 1,500 parts, among them Toshiba low-noise FETs. The boards are gold-clad custom ceramic types of the kind used in RF work, and they are shock mounted. Pass had capacitors made to its own specification and improved the shielding over the XP-25 to lower noise. The outboard power supply is itself dual mono, with a separate transformer, filtering and regulation for each channel. A switchable high-pass filter rolls off at minus 3 dB from 20 Hz downward for records with warps or rumble. Settings for gain and loading are stored for each input and recalled when that input is selected, so three different cartridges can stay connected with their own values. There is no power switch, as the unit is meant to stay on, and it draws about 55 W. No remote control is supplied.

Pairing

Since both output types are active, the Xs Phono can feed a balanced line preamplifier such as the Pass Xs Preamp or a single-ended one without adapters. The highest gain setting and the lowest load step match cartridges with very low output, and the lowest gain with the highest load step cover higher-output designs. Leaving the unit powered around the clock should be planned for when choosing a shelf with room for both boxes and free airflow around them.

Alternatives

The Pass Labs XP-27 is a smaller phono preamplifier in the current range for buyers who want the brand's circuit ideas at a lower price and in less rack space.