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47 Labs Model 4733 Midnight Blue Headphone Amplifier-Preamplifier-USB DAC Review

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47Labs 4733 Headphone AmplifierAfter going to CanJam at the RMAF, $2,000 doesn’t sound like so much for a headphone amp. Heck, before I went to CanJam I had no idea how big a deal headphones are nowadays. For those who haven’t caught on cans, people seriously into their cans want more than an iPod to play them on. So the new headphone/pre-amp from 47 Labs, may be just what some of you are looking for. Especially, one that is also a very good preamp and has a first class DAC built-in.

Still, this is a rather specialized product, like all 47 Lab products. They were first known for their original and simple Gaincard amplifiers. Like those, the Midnight Blue line of products are small and not very impressive looking. Cute, though. There are two 47 Labs products that are rather spectacular exceptions, the KOMA Turntable and the PiTracer digital transport. Both make an incredible visual impression. Yet, despite its simple appearance the Model 4733 Midnight Blue is possibly one of the most flexible headphone/pre-amplifiers out there. It incorporates a headphone amp with an active pre-amp and an onboard DAC with both coaxial and one USB input, as well as two line inputs. It also has a 2-watt amplifier, which will allow it to even drive small computer or very sensitive speakers. This at first to me really makes it an integrated amp with a great headphone output. It is so good as a headphone amp, though I now think that’s the way it should first be considered.

Design and Setup

The amplifier section of the 4733 is loosely based on the 47 Labs Gaincard amps. It uses a very simple circuit and opamp to produce its two watts of power. It uses an active and not a passive lines stage. I’ve been a fan of 47 Labs digital gear, especially our publisher Constantine’s PiTracer. If you’ve read any of my digital review you’ll know there is one thing 47 Labs designer and I agree upon; neither of us are fans of upsampling. We like non-upsampling DACs. The 4733 uses the Burr Brown 2707 DAC chip which outputs at 16 bit/48 kHz and uses no upsampling or digital filtering.

Of course, for those of you wanting to play high definition files in their native format, the 4733 isn’t for you. Truth is that it’s clear 47 Lab products have never been meant for everybody. If you want to hear some really great sounding music over a very simple but versatile product, the Midnight Blue headphone/preamplifier may just be what you’ve been waiting on.

Setting up the 4733 is very straightforward and simple once you’ve decided how you are going to use it. To use it is as simple as connecting it to a source. If you choose to use it as a Preamp/DAC all you need to do is connect it to an amp. If you want to use it as an integrated amp just hook up some speakers and a source. Most of all, if you’re going to use it for a headphone amp simply hook up your sources and plug in the headphones.

The way to use it that I found really amazing, was as a headphone amp. What makes that so amazing is I don’t even like to listen to music over headphones except on the plane or BART train. I went through a stage in the nineties when I tried high-end headphones and amps. If memory serves me right, I bought a Melos headphone amp and a pair of the top-of-the-line of Grado headphones then. When that didn’t please me, I tried the Stax electrostatics that came with the tube headphone amp. Both of these were great headphones. It turned out there was just one problem, I don’t like headphones. Even so, I wish my Klipsch in-ear phones and iPhone could always sound like they do when played through the 4733.


I used the 4733 in all its many configurations. As far as headphones go I used it mainly with three pairs: Grado’s SR 80i headphones (an entry level), Grado’s RS1i headphones, and the Klipsch’s top-of-the-line Image X10i In-Ear Headphones. By the way as I said in my review, these Klipsch are the best in-ear headphones I’ve heard without spending four times as much on a comparable competition. For sources I used my iPhone, a Marantz Blue Ray/SACD player, a Mac Mini, and for the heck of it, my Shindo turntable with a TubeGuru phono stage.

As a headphone amp, the Midnight Blue Model 4733 sounds clear and pure with great musical flow. It never had any strain or edge. Compared to the sound coming out of the iPhone’s headphone output to the sound when using the 4733 is night and day. It’s like moving from a very cheap moving magnet phono cartridge to a world class moving coil with a world class tube phono stage. It was even a major step up from my Peachtree Audio’s Decco Integrated amp’s headphone output.

Midrange and Top End

The 4733 in the midrange all the way through the top end has clear, clean, and transparent sound that lets music come to life. Voices were simply beautiful, and it handles male and female singers equally well. The amount of inner detail reminded me more of electrostatic headphones than the Klipsch I was using. The top end was very extended and very smooth. The Midnight Blue Model 4733 simply has an exceptionally musical and emotional involving midrange and top end.


I have a little time talking about bass with headphones; it’s not that they don’t go deep, they do. It’s not they can’t be tight or boomy, they can. It’s just that headphones don’t give me the same kind of visceral experience that a big pair of speakers do. Still the Midnight Blue 4733 gave me tighter, lower, and more tuneful bass than any other headphone amp I have heard. The bass is exceptionally tight, and has great punch.

Soundstage and Imaging

I was rather surprised at how much better this area was with the 4733. Both voices and instruments occupied their own space and had a distinctive amount of air around them. The soundstage didn’t seem to be quite so confined to my head as usual with headphones; there was actually some width and depth to be heard.

Now for something a little ridiculous

Just for the fun of it, I took this little jewel down to my big rig and replace my Shindo Giscours with it. I used the TubeGuru phono stage and the same computer audio setup as sources. Well, let me just be honest, it falls short in comparison to the $28,000 Shindo Giscours. Still it was very musical and most of its faults were omissions. It was never bright, or overly digital sounding. It had very nice detail and imaging, but by comparison was lacking in scale, power, and musical flow. Well anyway, I said this was ludicrous, but it did let me hear the quality the little 4733 is capable of.


The Midnight Blue 4733 is quintessential 47 Labs in the best sense of the word. That is musical, emotionally involving; and at the same time clear, transparent, and detailed. As a headphone amplifier it is simply amazing, as a preamp it would be very good if that’s all it was, and as a DAC it is on the short list of $2,000 DACs. The power amp is pretty limiting though, it’s great as a computer amp, but it’s not really up to driving large speakers even if they are very efficient. I should admit that it never claims to be. If you’re on a budget and have a need for a preamp DAC, or headphone amp, or both then I don’t think you’ll do much better than this.

In one way I hated this review; it has ruined listening to music on my iPhone for the foreseeable future. Every time I listen on my iPhone I wish it was playing it through the 4733. Why oh why can’t Apple and 47 Labs collaborate on an iPhone with a DAC and amp built in? Well, a man can dream, can’t he? Who would have ever believed there could be iPods and iPhones. (Also see Jack’s Review of the 4730 Midnight Blue tuner. -Pub.)

U.S. Importer’s comment:

Dear Dagogo,

Thank you very much for the Review. I wish all 47 Lab reviews are all like this! Jack does understand the idiosyncrasy of 47 Lab and its merits. I really appreciate that.

Best regards,


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3 Responses to 47 Labs Model 4733 Midnight Blue Headphone Amplifier-Preamplifier-USB DAC Review

  1. John Ruf says:

    Would you be brave enough to suggest some speakers that would work with my iMac and the 4733? Currently I use the old SoundSticks from HK. Thanks for a great review. I think 47 Labs is my answer to audio. They allow you to spend your time finding new music and not search for the gear to play it.

  2. Dagogo Staff says:


    Thank you for your email and readership. Please provide the following information and we will see what we can do:

    1. Size of your listening room;
    2. Your budget;
    3. Make and model of your power amplifier.

    Dagogo Staff

  3. lostnamerica says:

    I know this is pretty late in the game of posting, but…My current set up is as follows:
    47 Labs 4733, Onkyo CD7030, and for the speakers I just bought a pair of Sparkler Audio S301B diva’ and this system at only 2 wpc is magnificent. Truly amazing sound with these little babies,(the diva that is), and I am not looking any more for the perfect set-up that I had been searching for. I have found it. Might upgrade to another spinner (NOS type) and just ordered the 47 Laboratories speaker cable (.40mm) and will see if that gets any better than my current speaker cabling of Chord Rumour 2. And I’ll just use the bare-wire connection further eliminating any interference (if any is present), anther if simpler is better…

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