How good is the sound on your iDevice? Chances are you don’t really know. Even if you’re running a $500 pair of Shure SE530’s, you’re still listening to the device’s analog simplification of the complex and fast-moving digital data stream, a process is handled by the digital-to-analog conversion (DAC) circuit. These can (obviously) be made small enough to fit into a hand-held and cheaply enough not to push the cost of an iPod into four figures. There’s actually a lot more information on those digital files, even the highly compressed AAC files that Apple uses, than the onboard DAC can handle. With a bit of exaggeration, it’s a bit like tapping the Hoover Dam with a kitchen faucet. Nearly all the docking connectors for home stereos simply tap into the iDevice’s analog audio output rather than going though the expense of doing the analog conversion itself. If you want to drop about $3000 on a studio-grade CD player, you may get an inkling of what a real DAC sounds like.
Kevin Halverson and Mike Hobson realized this back in 2008 and formed High Resolution Technologies. They dedicated themselves to coming up with an affordable way to take advantage of all the sound that’s in a digital audio file using a device that the average audiophile would be able to afford. Soon after, their first product, the Music Streamer arrived, bringing pro-quality digital-to-audio conversion to desktops and laptops for under $200. At Macworld this year, they announced the iStreamer, specifically designed for Apple’s iDevices. Though the iStreamer is just starting to trickle out into the supply chain, they loaned one to MacDirectory to see if we could hear the difference.
At a Glance The iStreamer is less than 5 inches long but rather heavy, thanks to its thick metal shell. One end has the analog RCA-type stereo connectors. (HRT also makes a Pro version of the iStreamer with balanced, XLR outputs.) The other has a mini-USB input (for power) and a standard USB with full Apple Docking Connector support. There’s also a series of LEDs indicating the sampling rate of the audio being processed. Though attractively sculpted, this is meant for the back of the stereo cabinet. To help keep the analog and electrically noisy digital signals well isolated, the iStreamer lacks a pretty face to display proudly alongside your other components. The iStreamer comes with its own docking cable and the aesthetically sensitive may want to buy an Apple dock for the sake of looks. (The box includes a docking cable, power adapter and stereo RCA cables.)
Apple Friendly Unlike some OEM’s, HRT has gone through the time and expense to jump through all the necessary hoops to build a device that plays nicely with Apple products--no nasty warning messages when you plug it in and our iPhone offered us the option of either using the iStreamer or its built-in speaker. It also performed all the necessary switching when a phone call interrupted our tests. As you would expect, the docking cable provides power and charging services.
To test the iStreamer, we created duplicate versions of a number of music tracks on our phone: one copy was the uncompressed file straight off a CD and the other used iTunes AAC compression. To test the sounds, we used a pair of Sony MDR-V6 studio reference headphone and a home theater system comprised of a Sony STR-DH810 100Wx7 receiver, a pair of legacy Infinity 1500 main speakers and a Hsu Research VTF-1 sub-woofer (the rest of the surround system wasn’t used for testing). For reference, we first did a number of listening tests without the iStreamer, listening to the iPhone directly through the Sony headphones and connected to the sound system, using the audio output from the phone’s headphone jack. It sounded okay, of course, and it was possible to distinguish between the AAC and uncompressed versions of the files, though not easily. As usual, the unforgiving Sony headphones did make the compressed versions of the audio rather unflattering.
Next, we plugged in the iStreamer and tried our first track.
Then, we put our socks back on.
Sound Check The difference, though virtually the entire sound spectrum, was immediately obvious. Starting at the bottom, all the bass was there, but it no longer boomed, it matched much more closely the original sound of the source rather than the overly rounded, boomy interpretation we’ve become conditioned to expect. Even the compressed AAC files had a noticeably more realistic bottom end.
Of all the textures of the sound we tested, the easiest difference to pin down verbally came with the higher frequency percussion, particularly cymbals and bar chimes. With the strong high frequencies and multiple lower frequency overtones and harmonics, most brass-based percussion instruments are absolute murder to reproduce digitally. Listening to passages featuring these instruments clearly showed how badly the analog audio output from the iPhone broke down, no matter what point we chose to listen: directly through headphones, through the home theater speakers or using the headphones connected to the receiver. Going through the iStreamer, the sound was consistently crystal clear, though the loss in the AAC versions was fairly obvious. From that point, it was fairly easy to hone in on specific other instruments, particularly those with complex acoustic textures, and start hearing real differences. Listening the receiver’s headphone output was equally pleasing. Even the less detailed AAC files sounded noticeably richer.
If you’re not one to cut corners when it comes to sound, the iStreamer’s $199 price tag makes it a bargain basement accessory. Our tests left us convinced that the better the sound system, the more obvious the difference that you’ll hear. At this point in time, the iStreamer is a one-of-a-kind product. Though there are other USB DACs available at under $1,000, the iStreamer is the only one built specifically (and with Apple’s blessing) for a docking port. If you’re a true audiophile wanting to listen to an iDevice though a quality sound system, using the iStreamer is an absolute no-brainer. It will open the spill gates and provide a rush of sound like you’ve never imagined.
Nice review but has the same major shortcoming like many other reviews of similar products - it compares the sound quality of the DAC with the quality of the iPhone etc. witho...
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Nice review but has the same major shortcoming like many other reviews of similar products - it compares the sound quality of the DAC with the quality of the iPhone etc. witho...