Pass Labs is a legend in the audio industry. No, really — they are. Any time you ask a group of audiophiles about amp designers deserving the label of “super hero”, Nelson Pass is right there. My favorite quote (paraphrasing): “if you take all the exotic parts out, and it still sounds great, it must be the design”. Said another way — there’s just no substitute for solid engineering.
In recent years, Pass Labs have continued their approach to solid engineering and last year (at CES, actually), Pass launched their top-drawer Xs series (apparently, the Xs — “excess” — is a happy accident) with a pair of mega-amps, the Xs-150 and Xs-300. This year’s introduction brought the matching preamplifier, the Xs Preamp. Pricing is still TBD (but smart money says north of $30k), but availability will be later this year. The final aesthetic remains to be tweaked a bit, closer matching to the Xs amplifiers. Here’s what we know so far:
The Xs Preamp applies lessons learned designing Pass Labs’ breakthrough XP-30 3-Chassis Reference Preamplifier, and the two Xs Series Amplifiers for which it is custom designed to deliver music. The Xs Preamp is quieter than the XP-30 and has an even more improved power supply. In appearance, it resembles the Xs Amplifiers and features two large chassis built with a true dual-monaural topology. Internally, it has been innovatively designed, especially in its use of high-quality materials.
Its several circuit boards are fabricated from materials sourced in many cases from the military and high-speed computer sectors for their superior performance. Pass Labs has optimized each circuit board through an arduous trial-and-error process for top performance in each of the functional areas for which a board is employed. Circuit boards for power supply circuits have different requirements than ones for gain stages. In the Xs Preamp, each board is optimized for its specific use.
Each of the Xs Preamp’s two channels has its own power supply board, each with a refined circuit design and layout. Their 100,000-microfarad (uF) capacitors are optimized for low noise and high performance through the use of a variety of materials, from highly reliable electrolytics to a custom polypropylene. Newly available silicon carbide semiconductors further heighten performance by dropping noise below the level of Pass Lab’s XP-30 Preamp.
The circuit boards for the gain stages have been completely redesigned for maximum sonic impact. They employ a direct-coupled (DC), ultra-symmetric gain path with high-bias Class A circuitry, and feature auto bias and DC-compensation to maintain peak performance.
As a result, the Xs Preamp opens up the soundstage, delivers a greater sense of space and layering, and provides a clearer window into the performance of reproduced music. An extra large, high-definition display addresses listeners’ desire to know a music system’s status even from across a brightly lit room. The 20-character display is easy to read and dimmable.
The Xs Preamp comes supplied with a remote control. Its rear panel includes 6 inputs, a tape loop, dual-power input connections, dual balanced outputs, and variable outputs for bi-amping and use with multi-room systems.
Shown here with a pair of Xs-300 amplifiers ($85k/pair), tied to a pair of Sony SS-AR1 loudspeakers ($27k/pair). Not sure if it’s silly or redundant to say that the combo was fantastic, but, whatever. It was — and it was the best I’ve heard these speakers sound.
