Beginner's Guide to the Best USB DAC Headphone Amps, 2012

Even very good sound cards cannot turn digitally stored music into genuinely top quality sound without a little help.

If you store most of your music on a Mac or PC, a dedicated digital to analogue converter will go a long way to making the investment in a fine pair of headphones worthwhile, delivering musical detail that goes unheard otherwise. Whether a concert hall ambiance or full on beat fest is your hearts desire, a good DAC/headphones will bring digitally stored music to life.

As we use more and more streamed content, DAC's will become even more valuable.

Music from smartphones can get a huge boost from a portable external DAC. These can be very small, indeed, and easy to take anywhere,

What a DAC Does

Music stored in digital form on a PC or phone needs to be converted to an analogue signal in order to be heard. Headphones respond to varying electrical impulses of an analogue kind and the best sound is only achieved by processes that interpret the fixed points of digital code in a subtle way. Fixed points in digital format need to become smooth flowing electrical signals without gaps or disjunctions.

This 'filling in' or reconstruction process needs to be subtle given how sensitive the human ear is and how many tones and colors a single musical instrument can achieve.

Some external DAC's are simply converters. The DAC's on this page all use USB as an input (and sometimes as a power source) as well as having amplifiers onboard.

Are Valves better than Solid State?

Most people will tell you that a top quality solid state system sounds at least as good as a tube system. Many prefer them, believing them to to be more accurate.

Some will say that solid state DAC systems always sound lifeless and cannot create a rich 3D musical field. I would not go so far as to use the word 'lifeless' but I would say tubes are my preferred option for pure pleasure in sound in the low and medium price brackets. buy a very good state DAC and you will get very good sound- as long as your headphones are good enough, of course.

Disadvantages of Tubes

They are big, hot and they break if you drop them! Portability is not a tube amp selling point.

Will an External DAC improve on iPod Sound?

Most iPods have good quality DAC's onboard so the answer is more likely to be 'no' than 'yes'. Having said that, sound beauty is in the ear of the listener and many people will swear on their sound system that a DAC improves iPod sound on quality headphones.

Is a DAC worth the investment for MP3's?

A good DAC can greatly enhance the playback of MP3's. This is especially true on a PC with a merely average sound card. Even so, you will not get as much from an MP3 as a lossless file format like WAV, FLAC, ALAC (from Apple) or WMA (windows) lossless.

Outputs On a Headphone DAC

Most headphone DAC's offer outputs other than a simple headphone jack. The NuForce for example has the headphone jack at the front and RCA and Coaxial outlets at the back (pictured right).

This means it can feed into almost any sound set up.

Best in 2012

Some of the systems below have been around for a while but have stood the test of time and are still worth thinking about.

Others are new arrivals in the last 12 months.

Audioengine D1

This looks like being the best new arrival in 2012. It is super easy to use with plug and play capability and no need for an external power source beyond USB.

It weighs less than a pound and is roughly four inches by four inches with a thickness of only one inch. It may not be quite as portable as the new rPAC described below but it will travel.

It uses 192kHz sample rates from the optical digital input. USB allows 96kHz. The top quality RCA outlets makes it a pleasure to use with speakers that have built in amps.

This could be a great hub for your sounds in an office or bedroom as well as a very fine headphone amp offering wonderfully rich, precisely delineated sound on your cans.

NuForce Icon-2

Released last year, this adds to NuForce's already impressive reputation in the world of HiFi.

The most impressive feature is the very low level of noise even at high volumes- either on headphones or speakers. Too many DAC Amps are packed into too tight a space leading to interference from the various components. This desktop model has no issues of this kind.

The 24W x 2 (4 Ohm) and 18W x 2 (8 Ohm) power output may not sound that impressive but it will drive reasonably sensitive speakers at high volumes as well as giving you faithful sound with very little hiss, jitter or choking of highs and lows on your headphones.

Hi-Fi Man EF2A

For the price, the EF2A is very hard to beat for sweetness of sound. Tube amps easily out-compete solid state systems in the less expensive price ranges and this one sounds as good as most SS DAC's at twice the price.

The conversion is a two stage process with a Burr-Brown PCM2702 chip set up front and the valves to smooth out the sound.

It will take RCA analogue inputs as well as USB.

It looks great too.

NuForce uDAC-2

This is a very popular mid priced unit that is small enough to be considered portable (unlike its bigger brother above). The aluminum shell will take some knocks, too.

The analogue output packs respectable a punch at 2V.

It offers analog RCA, digital coaxial or headphone outputs and can make a laptop or PC the center of a versatile sound system.

FiiO E10- inexpensive but capable

This is the successor to the very popular E07 that introduced good quality coversion at a low price point.

The E10 has a tough aluminium casing to reduce interference. Maximum out put is 96 Hz/24 Bit. The bass boost makes it a favorite for club sounds.

It has all the software to install automatically on newer Macs and Window PCs.

Portable DACs

FiiO E11

The E11 has won plenty of admirers since its launch in mid 2011. It is very compact but packs a punch, turning devices like smartphones, MP3 players, iPods and laptops into capable music players on the move.

Arcam rPAC Portable- best new arrival in 2012?

The rDAC digital to analoque music converter from Arcam was one of the big successes of 2011. Its little brother the rPAC should offer similar music quality for headphones and is truly portable.

It will work with Mac or Windows OS and draws all the power it needs from the USB connection

It uses the kind of DAC component usually only found in top HiFi ste ups. Arcams circuitry is well known for faithful sound reproduction. The aluminium case makes it a tough traveler.

It is expected to hit retail in the second quarter and will sell for around $300.

• Grado Prestige Series SR225i Headphones. Not as comfortable to wear, maybe, as the Sennheiser below but an interesting retro design and dynamic, detailed sound and great customer service. The 32 Ohm impedance makes them ideal for lower powered portable devices. Around $200.
• Sennheiser HD 650. These 300 ohm headphones need plenty of power to sound good. Then they will sound very good, indeed. Pairs especially well with the Audioengine DAC described above. Around $500

• HiFiMan - HE-300 . 50 ohm. Great sound from a low impedance set. Around $250.