QUAD PA-One Valve Series
Vacuum tube headphone amp/DAC/preamp
QUAD PA-One Valve Series - Delivers smooth, dynamic sound to high-performance headphones (not included)
QUAD PA-One Valve Series - A special "Demo Days" listening session at Crutchfield HQ featuring the QUAD PA-One amp
Our take on the QUAD PA-One Valve Series by Crutchfield's Jeff Miller
Smooth, musical sound through your headphones
Vacuum tube amplifiers are known for delivering detailed and transparent sound, that's never too harsh. And the British hi-fi company QUAD has been working with tubes since 1940. So they knew the right chords to strike when they created the PA-One headphone amp. They use the term "valves" across the pond, but the beautiful glowing glass and familiar sonic characteristics are universal.
Just don't think this amp is only about the warm feeling of nostalgia. The PA-One is ready to work with modern music sources — there are digital and analog inputs, along with a high-resolution digital-to-analog converter. And it will make the latest and greatest high-end headphones really sing.
Crutchfield Demo Days with the QUAD PA-One amp
Crutchfield's Demo Days setup included our honorary employee: "Hedley" the mannequin.
Big thanks to our hardworking "Demo Days" crew! They recently set up the QUAD PA-One Valve Series headphone amp on the top floor of Crutchfield HQ, so we could all spend some time with it. Our music source was the stellar Sony HA-PZ1ES high-res audio player, connected via balanced XLR cables. We learned it takes about 15 minutes for the tubes to warm up for use — but it was well worth the wait.
We enjoyed several headphones through this listening rig, but the unanimous favorites were the Klipsch Heritage HP-3 over-ears. These top-shelf headphones paired so well with the PA-One amp, it was as if they were made for each other. Everyone seemed to walk away impressed — the music lept at us with such clean, powerful clarity.
Many of us gravitated toward a 24bit/44.1kHz version of the Beatles' Abbey Road. It was a particularly strong example of the dynamics and spot-on stereo imaging offered by the QUAD/Klipsch combo.
"Look, I've heard this album hundreds of times," said Crutchfield editor — and local guitar legend — Charlie Pastorfield. "I've listened to the Mobile Fidelity half-speed vinyl pressing through a friend's high-end system, and I still heard details through this headphone setup that I've simply never heard before anywhere. Really impressive."
- compact, high-performance headphone amp with vacuum tubes
- combines classic tube amp sound with modern digital features
- tubes provide dynamic, consistently smooth sound
- high-resolution 24-bit/192kHz digital-to-analog converter
- five amplification vacuum tubes:
- 2 x 6SL7
- 2 x 6SN7
- 1 X EZ81
- high-output power amplifier: 500mW at 32 ohms
- digital audio inputs: 1 USB (Type B), 1 optical (S/PDIF), and 1 coaxial (S/PDIF)
- USB driver required for Windows® users; available here
- stereo unbalanced RCA audio input
- 1 pair balanced 4-pin XLR line-level inputs
- 2 full-size 1/4" headphone jacks
- 1 pair stereo RCA outputs for connection to a compatible audio component
General Info and Specs:
- detachable AC power cord
- signal to noise ratio: 105dB
- output impedance: 32-300 ohms
- frequency response: 20-40,000 Hz (0.5dB)
- 7-1/8"W x 6-1/2"H x 11-1/4"D
- weight: 16.5 lbs.
- warranty: 2 years
- Our 60-day money-back guarantee
What's in the Box:
- Headphone amp / preamplifier
- 6' AC power cord (IEC 3-prong)
- 62" USB cable (Type A USB on one end and Type B USB on other end)
- Phillips-head screwdriver (to access tubes)
- Software on mini CD-ROM
- Owner's Manual
QUAD PA-One Valve Series Reviews
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Overview: The Quad PA-One is a combination headphone amp, D/A converter, and preamplifier. The PA-One is equipped with five vacuum tubes (or "valves", as the British call them) to give you the most lifelike sound possible. It has both analog and digital inputs, two 1/4" headphone outputs, and an RCA preout. The PA-One is housed in a sturdy steel chassis with a Lancaster Grey finish.
Design: The PA-One's classic design is based on Quad's benchmark Quad II valve amplifier from 1936. Engineers have carefully selected two 6SL7, two 6SN7, and one EZ81 high-amplification vacuum tubes to deliver its trademark high fidelity sound. Tube amplifiers require a "warm up" period of at least 15 minutes prior to use for best sound quality, and to prevent damage to your equipment. Also, an extended "burn-in" period of at least four hours, and preferably, twelve hours, is highly recommended before you first use it. More information on warm-up and burn-in can be found in the included Owner's Manual.
Digital-to-Analog Converter: The PA-One features a USB DAC to allow you to listen to your favorite digital music sources from a computer or laptop via USB. It is USB 1.1 and 2.0 compliant, and is compatible with both Windows and Mac. A 5' USB cable with gold-plated USB-A and USB-B connectors is included. The DAC supports sampling frequencies from 35kHz to 192kHz. You can also connect your other digital components to the PA-One via optical or coaxial digital cables.
Connections: The Quad PA-One offers two headphone outputs and a variety of analog and digital inputs:
- Headphone Outputs: two 1/4" jacks (front panel)
- Line Input: pair of gold-plated RCA jacks
- Balanced Input: pair of left and right XLR jacks
- Digital Inputs:
- USB: Type B USB
- Coaxial: single RCA jack
- Optical: Toslink optical input
Controls: The PA-One has a large rotary volume knob on the front panel with a balance control just below. Source selection consists of three push buttons for the Line Input (RCA), Balanced (XLR), or Digital inputs. The Digital Input button allows you to cycle through for selecting the USB, coax, or optical sources. A 2-way Impedance Selection switch lets you toggle between low and high impedance headphones. The main power switch is located on the back panel.
- Frequency Response: 15Hz - 30kHz (+0.5dB, -0.5dB)
- Input Impedance: 50kΩ
- Input Sensitivity: 300mV (500mW @ 32Ω
- Output Impedance: 32Ω - 300Ω
- Output Power: 500mW @ 32Ω
- Digital Resolution: 44.1kHz, 48kHz, 88.2kHz, 96kHz, 176kHz, 192kHz
- Channel Balance: +/- 0.5dB
- Distortion: 0.5% @ 1 kHz
- Signal-to-Noise Ratio: 105dB
- Dimensions: 7.06" width, 6.5" height, 11.43" (13.375" including power cord)
- Weight: 16.53 pounds
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Why did you buy this?
Reviews [ Barry Apr 25, 2018 ]
1 question already asked
The Tubes are used for all of the analog audio outputs; including the RCA pre-out, yes. I hope that helps. My bio: https://www.crutchfield.com/bio/Ryan [ Ryan Mar 31, 2018 ] Staff