There are people who do not know that Wayne Colburn has designed the Pass Labs preamplifier products for the last 20 years. Wayne’s modesty
has tended to keep him out of the spotlight. When Pass Labs began development of the Xs power amplifier five years ago, they knew that a companion piece would be needed. Back then they thought they could have this done in a year or so… Wayne was given carte blanche on the design and an
unlimited budget, and lots of time to play with many exotic parts and materials.
Naturally the comparison will be made with its predecessor, the XP-30 line stage preamp. The most obvious difference is that the Xs pre-amplifier comes in only two chassis, where the XP-30 had at least three chassis, one for supply and control, and one chassis per channel for as many channels as you might reasonably want.
The Xs pre-amplifier is designed solely for two-channel operation, and it fits in two (larger) boxes. The volume controls are improved in performance with 0.5 dB steps, expanded dynamic range and lower noise.
The buffer stage for the volume control has been eliminated, giving an even simpler gain path. Improved circuit boards layout puts the cherry on top. Some of the materials are more exotic—the gain stages are mounted on ceramic circuit boards with gold plating.
The channel motherboards are made of Panasonic Megtron with immersion gold, which performs about as well as Teflon or Polyamide but without the adhesion properties. The power supplies use 4 ounce high temp FR406. While the two channels share a chassis, they are isolated on separate board systems with distance between them, crosstalk figures between channels are as good as the XP-30 separate chassis.
The three separate power supplies use the lowest noise transformers available and they incorporate filters on the AC line input, fast/soft recovery rectifiers, large storage capacitance and extensive regulation. The active regulation is followed by passive filtering using polypropylene capacitors. All this in machined aluminium cases. If your eyesight is not what it once was, you will also appreciate the larger display. It does not automatically follow that more money and more exotic parts and such will result in a better sounding product. Fortunately there was lots of time available, and the back-andforth process between Wayne and the four other listeners assured the finest product Pass Labs could possibly make.
Overall Gain: -89.5 dB to +9.5 dB
Volume Steps: 99
Frequency Response: -3dB @ 2 Hz and 60 kHz
Input Impedance: 42k balanced
Output Impedance: 120 Ohm bal, 120 Ohm SE
CMRR: -65 dB, 1 kHz
Cross-talk: -100 dB, 1kHz Ref 1V
Signal to Noise Ratio: < -110 dB, Ref 5V
Power Consumption (W): 55
Number of Chassis: 2
Dimensions, Each Chassis: 19”W x 14”D x 6.25”H
Weight (LBS): 80
Shipping Box Dimensions: 24 x 19 x 23
Shipping Weight (LBS): 90