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Pro-Ject Head Box S

Headphone amplifier (Silver)

21 Reviews | 5 questions - 19 answers

Item # 252HDBXSS

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Our take on the Pro-Ject Head Box S

Top-notch headphones are a great way to experience reference-quality sound for a fraction of the price of a high-end loudspeaker system. But if you're plugging your 'phones straight into the headphone jack on your stereo or PC, you could be missing out on the subtle differences that separate great recordings from the merely good ones. That's because a lot of manufacturers use low-cost, low-fi circuitry to drive their headphone jacks — leaving you with uninvolving, one-dimensional sound.

Give your headphones the power they deserve

Top-notch headphones are a great way to experience reference-quality sound for a fraction of the price of a high-end loudspeaker system. But if you're plugging your 'phones straight into the headphone jack on your stereo or PC, you could be missing out on the subtle differences that separate great recordings from the merely good ones. That's because a lot of manufacturers use low-cost, low-fi circuitry to drive their headphone jacks — leaving you with uninvolving, one-dimensional sound.

Headbox s back

Enjoy a big sonic upgrade

Pro-Ject's Head Box S headphone amp delivers the power you need to bring out the best in your headphones and your tunes. Connect it between your music source and your 'phones to experience richer, deeper bass, clearer highs, and gobs more detail. You'll also hear farther into your favorite recordings for that "you are there" feeling.

Excellent, Additionally I was concerned that it wouldn't have enough power to drive sennheiser HD600 but I can't even pass the half way mark on the volume dial. It is small and esthetically beautiful

Mehmet, New Rochelle, NY

What's in the Box:

  • Headphone amplifier
  • AC power supply (with attached 5' DC cord)
  • Instructions For Use

Product Highlights:

  • low-distortion headphone amplifier
  • front-panel on/off switch
  • full-metal housing protects against interference
  • recommended headphone impedance: greater than 30 ohms
  • THD: 0.003%
  • frequency response: 30Hz to 20kHz at -0.05dB (10Hz to 120kHz at -1dB)
  • signal-to-noise ratio: 95dB at full output (A weighted)
  • gain: 11dB
  • connections:
    • 1 pair line-level RCA stereo audio inputs
    • 1 pair line-level RCA stereo audio outputs
    • full-size 1/4" stereo headphone output
  • outboard power supply with 5' DC cord included
  • weight: 21 ounces (without power supply)
  • 4-1/16"W x 1-7/16"H x 5-7/8"D
  • warranty: 2 years
  • Our 60-day money-back guarantee

Pro-Ject Head Box S Reviews

Average Customer Review(s):

(21 Reviews)
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Hands-on research

Product Research



Overview: The Pro-Ject Head Box S headphone amplifier is a compact audio amplifier designed particularly to drive headphones. The external headphone amplifier allows for higher possible volumes and greater audio clarity than the smaller, inexpensive integrated headphone amplifiers that are used in most of today's home receivers or audio players. The Pro-Ject headphone amplifier connects to a line-level (RCA-type) input & output of your AV receiver or directly to the line-level (RCA-type) output of your audio source.

Note: Available with a black or silver front-panel.

Construction: The Pro-Ject Head Box S headphone amplifier employs a metal case to shields the circuitry from vibration and electromagnetic interference.

RCA Input/Output: The Pro-Ject Head Box S headphone amplifier features gold-plated stereo input and output RCA phono jacks. The headphone amplifier's connects to your AV receiver's Tape monitor or CD-R/DVR inputs & outputs. It can also connect directly to your audio source's (CD player, Tape, Turntable) audio output.

Headphone Output: The Pro-Ject Head Box S headphone amplifier is equipped with a front-panel 1/4" headphone jack to plug in your headphones.

Volume Control: The Pro-Ject Head Box S headphone amplifier features a front-panel rotary volume knob to control the volume level of your connected headphones.

Power Requirements: The Pro-Ject Head Box S headphone amplifier operates off of standard household current using the included oversized outboard power supply.


Headphone Jack: 3-pole, 1/4"

Gain: 11dB

Power Output: 330mV/30-ohms, 60mV/300-ohms

Headphone Connection: >30-ohms

Signal-to-Noise Ratio: 95 ref. full output (112dB-A weighted)

Frequency Response: 30Hz-20kHz (+/-0.05dB), 10Hz-120kHz (-1dB)

THD: 0.003%

Power Supply: Input = 100-240V ~ 50/60Hz, max. 0.6A / Output = 15V - 500mA (18V)

Power Consumption: 18V/100mA

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Q & A

Customer Q&A

Crutchfield asked  
Why did you buy this?

Good price, just wanted a headphone amplifier, to listen to TV. [ THERESA  Apr 27, 2017 ]
Work component [ Scott  Mar 22, 2017 ]
it's ok. i don't find much difference in headphone amps, to be honest. [ Daren  Jan 16, 2017 ]

5 questions already asked

I'm sure it would help and provide a better source than the standard headphone jack found on most receivers [ Stephen  Jan 17, 2017 ]
This unit only has RCA line-level inputs, so I'm not sure how you would connect your phone to this. It should drive the headphones though. I think you should look to getting an amplified DAC instead. [ Daniel  Jan 07, 2017 ]
You won't need a pre-amp. I've used the Head Box S straight out of a Roku Soundbridge and a Logitech Squeezebox Touch and it works great. Neither of those devices have pre-amps. [ jeffrey  Dec 12, 2016 ]
You will need a preamp. This unit only has line-level inputs. [ Daniel  Dec 03, 2016 ]
Robert...I tested this for you with a pair of Sennheisers 600s. I hooked the amp up to my computer, i phone and ipod. It was close but no cigar. I used the 600s for two reasons..1. they are the closest headphones in existence to your 650s, and the impedance on both is 300 ohms. That's a ton of resistance and it doesn't quite do it for you. You'll need a slightly stronger amp. I posted something very close to this answer originally but never saw it. It appeared as though you thanked me for my next comment which wouldn't have been helpful at all. I noticed someone else said that their m50xs do fine with this amp. He's right, but the impedance on m50xs is very low in comparison. [ William T.  Feb 28, 2016 ]
All I can say is that it makes my Audio-Technica headphones sound like alive show. My laptop sounds like it has 200 watts [ jeffrey  Feb 28, 2016 ]
Plus, You have a pair of fine headphones. A ton of people swear by their sound. Do yourself a favor and really research it. If you don't, you may not get to experience the incredible sound that they produce. [ William T.  Feb 28, 2016 ]
Hi, Robert....My opinion is not quite. I use it a chain with a second amp that are plugged into the audio port on my computer and it gives me what I need, but not with the Head Box S all by itself. When I saw your question, I plugged my I Phone 6s into it and it didn't quite make it. Same thing with my I Pod Nano. I'm using a pair of Sennheiser 600s to test it out. The reason I'm using them is that they're the closest thing I have to your headphones plus the impedence is the same in the 600s and 650s. 300 ohms...That's a lot of resistance. You need to go up one level. It's close, but not quite. Here's part of an article I just googled: "The real number we're concerned with, however, is the HD650's 300 ohms of impedance. As with other Sennheiser open-air headphones, they have a high impedance that requires not only a powerful amp, but a quality amp. To get the most out of these headphones, you'll need something good." [ William T.  Feb 28, 2016 ]
I have Sennheiser HD600's and it does fine. [ Gloria  Feb 28, 2016 ]
I'm sorry but I don't know the answer to your question. [ Maurice  Jan 26, 2015 ]
I have never used the RCA output jacks. I would also assume that the unit must be powered on for the signal to pass through. I would also guess the RCA output is non-variable, but don't know for sure. [ Edward  Jan 25, 2015 ]
Not sure, I haven't hooked it up or tested it in that configuration. [ Patrick  Jan 25, 2015 ]
I have a signal coming from a optical source which I needed to control the volume, the Crutchfield tech service suggested the Pro-Ject Head Box. I am feeding the signal into the input side on the rear of the Head Box and have a large stereo adapter on the front output where I connect the 3.5 mini stereo ear bud. In order to answer your question I connected the RCA to 3.5 cord to an earbud which I receive where I receive the non controlled volume feed. Hope thats helpful. My name is JackW. [ JACK  Dec 22, 2014 ]
No they are not automatically muted when you plug in the headphones. [ LINCOLN  Dec 10, 2014 ]
Sorry, but I don't exactly know what you're asking. In the setup I have, when the headphones are plugged into the amplifier which is connected to the RCA output of the cable box, it has no effect on the sound coming from the t.v. because the t.v receives the sound from the cable box via an hdmi cable, not from the RCA output. They are two separate functions that do not effect each other. [ Maurice  Dec 10, 2014 ]
Thank you Patrick. It looks like this will fit the bill as I am trying to get the headphones off line from the other gear. [ Keith  Dec 10, 2014 ]
No. Also the rca output is at a standard volume, the adjustment knob doesn't change it. [ PATRICK  Dec 10, 2014 ]
Sorry Keith but I only use it for the headphone jack. But it does make sense since head phone jacks usually over ride outputs [ BERNARD  Dec 10, 2014 ]
Don't know, haven't used it in that configuration. Sound output is really good using Grado SR225 phones, could use a remote for volume control though. [ Patrick  Dec 10, 2014 ]