The newly introduced XA.5 series incorporates all the improvements of the new X.5 series (see below) and also operate pure Class A. The distortion is even lower, the control is even better.

More importantly, the XA.5 amplifiers have tremendously larger output current capacity over their corresponding XA models – more than five times the current – which is more than 25 times the power into very low impedance loads. Very difficult loudspeakers are now very appropriate loads for XA.5’s.

Sonically the result is:

Greater power and control – No matter what your loudspeaker, the X.5 and XA.5 power amplifiers have the power and stability essential to deliver the music without strain. They have the dynamic range to do justice to the 24 bit recordings of the 21st Century and the elegance to retrieve the micro dynamics offered by the most sensitive loudspeakers. This simplicity and power moves easily from total silence to explosive transients with ease and without information loss.

More music - These are not simply good high power amplifiers. They have been designed by lifelong audiophiles to deliver the warmth, sweetness, depth and space that are the hallmarks of fine audio products. Most importantly in this regard, the X.5 and XA.5 amplifiers are significant improvements on their classic predecessors.

Pass Labs continues to improve its power amplifiers. After five years, these acquired enough mass to warrant a change in designation, and the X.5 series was announced. The improvements are:

Cascode JFET Symmetric front end – input differential MOSFETs have been replaced by the same JFETs we use for the input devices on our MM and MC phono stages. They have very much less noise, higher input impedance, and greater linearity. They operate self-biased in a symmetric quad topology, each device cascoded and level shifted to form the full voltage gain stage of the amplifier.

More power output devices – Greater quantities of matched complementary power Mosfets operated as followers, giving more current and power handling, and also improved linearity.

Single-ended Class A bias – The output stage not only uses a heavy bias current for push-pull Class A operation to a large portion of the rated power, but also has a single-ended bias source for single-ended Class A at low wattage.

New bias circuit – A newly developed bias generator has eliminated three sources of variation in bias current in the output stage. It also allows approximately 20% greater power output for a given supply voltage.

Improved power supplies – The power supplies have been given greater storage capacitance, larger / quieter power transformers, fast recovery rectifiers (twice as many), and improved harmonic filtering in both the primary and secondary supply circuits.

Better layout – All portions of the amplifier circuitry have been refined with respect to wiring and circuit board layout so as to achieve lower noise and distortion and greater reliability and serviceability.

The INT-150 is Pass Labs’ first integrated amplifier. Based on the X-150.5 Stereo Amplifier, the INT-150 embodies the design technology and refinements — including patented Super-Symmetry™ circuit — of the X150.5 and Pass Labs’ larger X.5-Series amplifiers.

In performance, the INT-150 boasts an excellent dynamic range and fast response. Rated at 150 watts-per-channel into 8 ohms, and 300 watts into 4 ohms, it moves easily from black background to explosive transients, then back again, adding realism and authenticity to recorded materials. It performs with authority and stability regardless of loudspeaker load. Smooth and transparent, the INT-150 provides clean, expansive sound at an affordable price.

The XP-10 and XP-20 are ultra high quality line-stage audio preamplifier featuring direct access remote control functions and in the case of the XP-20 an external power supply isolated from the analog circuits of the preamplifier in a cosmetically matched second chassis.

The new XP series pre-amplifiers are more true to state of the art recordings than our previous product. Highly dynamic passages typically have more weight; bass lines are more clearly, cleanly, and accurately delineated. Instruments and voice are presented in a more refined spatial envelope, and with better spectral balance. Fine nuances and details become apparent -- even in loud and highly complex musical passages.

The XP-15 is a single chassis successor to Pass Labs’s award-winning Xono phono-stage. It features lower noise levels, greater resolution, better base control and an attractive single-chassis design. It’s superb construction only suggests the quality of the listening experience it delivers — a lush, smooth sound with a wide stage and firm bass. The XP-15 is easy to set up and a pleasure to use, especially given that the best of today’s vinyl is significantly better than what was available when vinyl was the mass-market audio media of choice

The new SR1 is Pass Labs’ second loudspeaker, following the Rushmore, its exceptionally dynamic introductory speaker.

The new SR1, a four-way floorstanding system, is equally uncompromising. Its highly refined sound stage, deep awareness of micro-detail, and effortless dynamics deliver superb, accurate musical reproduction.

The SR1’s drivers are the best available, and employ Nextel-coated cones and a Crescendo tweeter from the renowned Seas of Norway. They present the best combination of low distortion, high dynamics, and predictable performance. It takes a minimum of four sizes of these drivers to span the SR1’s 10-octave audio range without significantly leaving the “piston” region.

The SR1 uses dual enclosures. A large bass enclosure with ten-inch and eight-inch drivers handles the bottom four octaves, and an adjustable smaller enclosure carries the midrange and the tweeter. The Seas of Norway drivers are complemented by a set of crossovers to elicit the drivers’ best performance.