Core Sound HeadLine™ Portable DAC, Headphone Amplifier and Source Selector
Have you ever been out in the field and needed to monitor an S/PDIF digital audio data stream but didn't have a portable DAC (digital-to-analog converter)? Have you ever wanted to monitor on headphones instead of speakers but couldn't find a portable DAC that had a pro-quality headphone amp? Have you ever wanted to listen to your favorite analog or digital sound source over a great set of headphones instead of the crummy built-in headphone amp and ear buds that came with your player? Have you ever needed to monitor both an analog source and a few digital sources? Have you ever needed to monitor a source and also drive another device's Line-level input? Have you ever wanted an audiophile quality DAC and headphone amp that's good enough to use in your home High End AV system and also portable enough to take on the road?
Core Sound's new HeadLine does it all!
HeadLine is the first portable, battery-powered, audiophile-quality device that combines a DAC, headphone amp and source selector. It allows you to select between three S/PDIF digital audio sources (two coaxial and one optical) and one analog Line-level source. A switch lets you select whether HeadLine functions as a Line-level DAC, headphone amplifier or both simultaneously. Unlike almost every other headphone amp on the market, it can effortlessly drive both consumer (30 Ohm) and professional (600 Ohm) headphones and in-ear monitors (IEMs). It will operate on a pair of common alkaline nine Volt "transistor radio" batteries for more than five hours. And when the batteries' voltage drops, you can continue listening while you swap them out one at a time for fresh batteries.
HeadLine is designed to be neutral in sound quality and add essentially no sound of its own -- it simply gives you what you feed it, only louder. It accepts 24-bit S/PDIF digital audio data at sample rates up to 192 KS/s. Its performance is outstanding: line-stage noise floor is typically down at -140 dB, separation between channels is typically 105 dB at 1 KHz and total harmonic distortion plus noise (THD+N) is typically down at 0.00055%!
HeadLine is powerful enough to drive speakers. It's a mini power amp rather than a milliWatt earbud driver.
HeadLine provides clear indications about the charge state of its batteries and external power supply. An LED on its front panel glows solid green when running on an external battery pack or AC wall wart. The green LED blinks when running on internal batteries that are in good condition. It turns yellow when the batteries' voltages drop to a point that you should start thinking about changing them. When the LED turnes red and starts flashing slowly, it's time to change at least one battery. As the batteries' voltages drop further, the red LED flashes faster. And finally, when the red LED stays on continuously, the batteries' voltages have dropped below what HeadLine needs to operate per its specifications.
HeadLine optimizes battery life by allowing you to shut down unused functions. If you're only using it as a DAC, you can shut down the headphone amplifier to save lots of battery power. If the Toslink input is not selected, the Toslink receiver is powered down. Also, when running on batteries, the S/PDIF Lock LED turns on for a few seconds when a valid data stream is detected, and then turns off.
Compare HeadLine to the Grace Design 902 ($1700), Benchmark Media Systems' DAC-1 ($975) and Headroom's Micro Line Micro Amp/Micro DAC combination ($600). You'll see that HeadLine ($399) offers audiophile quality performance and more features at a significantly lower price. And HeadLine is portable!
HeadLine Specifications
Channels: 2
S/PDIF Digital Inputs: 3 (two RCA coaxial jack, one Toslink optical jack)
Word width: 16 to 24-bits
Sample rates: 32 to 192 KS/s
Analog Input: 1 pair, stereo Line level (dual RCA jacks)
Headphone Output: 1/4-inch stereo phone jack
Line Outputs: 1 pair, stereo Line level (dual RCA jacks)
Controls and Indicators:
Power Off/Line/Both Line & Headphone Select
Headphone Level, continuously variable
Analog/Digital Source Select
Digital Source Select
S/PDIF Data Valid LED
Power Supply Voltage Status LED
Line output specifications:
Frequency response: typically 20 Hz to 20 KHz, +/- .1 dB
Noise floor: typically -135 dBFS
THD+ Noise: typically -105.5 dBA (< .00053%), 22 Hz to 30 KHz
Crosstalk: typically better than 112 dB @ 1 KHz; better than 85 dB, 20 Hz to 20 KHz
Output for 0 dbFS input: 1.88 Volts RMS (5.48 Vp-p/7.7 dBu)
Dimensions: 1-3/8"H x 6-9/16"W x 3-3/4"D (34.9mm x 166.7mm x 95.3mm)
Weight: 10.5 ounces (300 grams)
Headphone output specifications
Output impedance: nominally 11 Ohms
Driving 600 Ohm headphones (e.g., AKG 240DF)
Frequency response: typically 20 Hz to 20 KHz, +/- 0.1 dB
Noise floor: typically -136 dB
THD+N (A-weighted): typically -98 dBA, .0013% at 700 mV RMS (low listening level), .005% at 8 Vpp (way, way too loud)
Separation: typically -93 dB @ 1 KHz
Output voltage: more than 5 Volts RMS (!)
Driving 25 Ohm headphones (e.g. Sony 7506)
Frequency response: typically 20 Hz to 20 KHz, +/- 0.1 dB
Noise floor: typically -136 dB
THD+N (A-weighted): typically -93 dBA, .0018% at 200 mV RMS (very loud), .005% at 850 mVpp (way, way too loud)
Separation: typically -93 dB @ 1 KHz
Output voltage: more than 800 mV RMS
Battery complement: two 9 Volt alkaline "transistor radio" batteries (type 1604)
Operating time for two batteries: 5 hours minimum at full load (Line and Headphone outputs driven; 12 hours typical for Line output only; (batteries may be hot-swapped for unlimited continuous operation)
External power supply: 7 to 16 VDC @ 250 mA (minimum) via 5.0/2.1 mm DC power jack
Each and every HeadLine is subjected to eighteen tests using an Audio Precision System Two Cascade before it ships to you. Core Sound is one of the few companies that tests its products this rigorously to guarantee that your HeadLine is as good as it can be.
HeadLine's frequency response is uncommonly flat and extended. With a -0.1 dBFS 24-bit/44.1 KS/s digital signal driving, here's HeadLine's Line-level output's frequency response.
Note the very expanded vertical scale on this graph. If we didn't expand the scale you would never see the roll-off. The frequency response is extremely flat, typically varying less than plus-or-minus one-tenth of a dB. (We've separated the two channels by a fraction of a dB so that you can see both of them.)
HeadLine's THD+N performance is also uncommonly good. Being driven by a -0.1 dBFS 24-bit/44.1 KS/s digital signal to an analog output level of 8 dBu (around 2 Volts RMS -- a very loud Line level), the noise baseline is typically more than 140 dB down from the signal, and the highest harmonic is more than 105 dB below the signal. That's .00055%!
Channel separation is typically more than 115 dB at 1 KHz and more than 85 dB at 20 KHz. Again, this is outstanding performance!
Configuration Jumpers
HeadLine has two internal user-configurable jumpers.
The first jumper controls the bandwidth of the phase locked loop (PLL) on the S/PDIF receiver. Some S/PDIF source devices (e.g., computer sound cards, CD players) have excessive jitter on their outputs. For folks who are listening to those devices the filter should be set to Wide Band; otherwise its PLL make may lose lock and mute.
For those who have high quality digital audio sources, this jumper should be set to Narrow Band. Setting this to Narrow Band gains another 1.5 dB of S/N ratio (up to 106.5 dB from 105 dB). To ensure that HeadLine works with all digital audio data sources, it ships with this jumper in the Wide Band position.
The second jumper controls whether non-critical digital audio data errors are flagged by lighting the red LED. Scratched or dirty CDs often have lots of data errors. The errors are not critical because they are corrected and not audible. If you want to be alerted to these errors, set this jumper to the other position.
Notes About Headphone Quality
In designing and testing HeadLine we discovered that some headphones are considerably better than others, and not just in the ways you'd expect (e.g., sound quality, distortion, sensitivity).
Some headphones have inherently very poor crosstalk specifications and can degrade even the best amplifier's noise and distortion specifications.
For example the very popular Sony MDR-7506 headphone's coiled cable and drivers degrade crosstalk between channels to -56 dB, the noise floor degrades to -126.5 dB and the THD+N specification degrades to -92 dB. Interestingly, if instead of using HeadLine to drive them, you used a Mackie 1202 mixer (or other similar quality headphone amplifier) to drive them, the crosstalk specification is degraded about another 10 dB! (The Sony MDR-7506 'phones have a nominal 30-Ohm impedance; we measured these specifications while driving them with 100 mVp-p signal, which is pretty loud.)
So while HeadLine is capable of incredibly high levels of performance, if you use headphones that can't take advantage of it, you'll get degraded performance.
Another example: compare the -7506's performance with the 600-Ohm AKG K240DF professional studio headphones. With the AKG, crosstalk is around -93 dB (compared to the Sony's poor -53 dB), noise floor is around -136 dB (compared to the Sony's still-pretty-good -126.5 dB), and THD+N is down around -96 dB (compared to the Sony's -92 dB). (We measured the AKGs while driving them with a 2 Vp-p signal, again pretty loud.)
So if sound quality matters to you, pick your headphones carefully!
HeadLine Ordering
HeadLine is priced at $399. We are happy to accept orders on-line and via PayPal (send payment to: orders@core-sound.com), phone, email, mail or FAX.
An AC adapter is $12.
Payment
Payment is via any major credit card (Visa, Mastercard or American Express), a PayPal account, personal checks, money order (available from the Post Office or bank), traveler's checks, wired funds, cash or certified check, US funds only. Please allow some additional time for personal checks to clear the bank prior to shipment. COD shipments are available in some situations -- contact us for details. You may wire funds directly to our bank account -- please contact us for details.
PayPal handles our credit card processing. You need not have a PayPal account to pay with a credit card.
We also accept purchase orders from pre-qualified US universities, corporations, and state and federal governments.
Checks should be made out to "Core Sound LLC" and sent to:
Core Sound LLC
405 Cedar Lane, #1
Teaneck, NJ 07666
USA
Orders are typically shipped within two or three days but delivery times vary with our order load. We can usually accommodate "rush" orders, including same day shipments -- call and ask!
If you have questions, call and ask for Len Moskowitz. He can be reached at (201) 801-0812. His electronic mail address on the Internet is:
moskowit@core-sound.com
Customs Taxes
If you are ordering from outside the United States or Canada, your government may (or may not) charge you import taxes. Those taxes are your responsibility. If you are not certain, please ask your local Customs authority for more information.
VAT and Sales Taxes:
Core Sound LLC collects only State of New Jersey sales tax. We do not collect UK/Europe VAT taxes or any other taxes
HeadLine Trial Offer
To give you a chance to try it and decide if it's for you, Core Sound provides a 30 day trial period. All HeadLines returned within 30 days of shipment qualify for a full refund (minus shipping and handling charges) provided that they are returned in as-new condition.
HeadLine Limited Warranty
HeadLine is sold with a one year limited parts and labor warranty. If a HeadLine requires repair during that period, ship it back to Core Sound postage-paid with a description of the problem, and then please call us once we have received it to discuss the problem. We will repair or replace it and ship it back to you at no charge. No consequential damages are covered by this warranty.
HeadLine User Comments
R.C., in Australia, wrote:
“I now have my Headline and I must say my initial impressions are very positive... It is a very robust looking and feeling unit - I can't believe how well it drives my 600 Ohm DT770's from a couple of 9V batteries! The only comparative test I have done so far is to spend about an hour with it connected to both the digital AND analogue outputs of a Cambridge Audio Azur 640C cd player. There is a toggle on the Headline which allows you to switch between digital and analogue source. This effectively enabled me to A/B the DAC of the Headline vs the DAC of the cd player, holding the Headphone amp constant. I used my DT770's and mainly listened to 'Duke Elegant' - a disc of Duke Ellington songs performed by Dr John. With both bits of gear you can hear the money that has been spent in this recording. I like the Headline's dac better on the strength of my short test. The cymbals sound more natural and the bottom end tighter and faster. His voice sounds great with either. In my home system I have a very old cd player feeding an old Cambridge Audio DacMagic 2 converter. As you would expect the dac in the Headline absolutely smashes this 10 year old box.”
[A few weeks later he wrote:]