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Positive Feedback ISSUE 54
march/april 2011


The World's Least Expensive Digital Music Server: an Apple iPad and the HRT iStreamer
by Andy Schaub


How does it feel to be

One of the beautiful people?

Tuned to a natural E

Happy to be that way.

Now that you've found another key

What are you going to play?


The HRT iStreamer ($199.95) was sent to me as a present by Lee Weiland at Locus Design and I had hoped that, like my iBasso D4 "Mamba", I could use it directly with my iPad with no AC power (in the case of the D4 "Mamba" requiring the camera kit for the iPad to give me a high-quality USB connection, a 9-volt battery and a Cardas mini plug to RCA cable). Sadly, it isn't so, as you do have to plug the iStreamer into an AC socket... which for some could be a bit of a hassle. Having said that, the AC adapter (technically an unusually pretty "walwart"), does have an extra USB port on it to power, say, your iPod Touch while you're listening to music on your iPad. Also, the HRT iStreamer is appears to destined for life with in an iPad. At least, that is how it sounded best, and even though I had 24/48 resolution files on my iPod Classic as well as my iPad, they would only play when the iStreamer was attached to my iPad. There's not much in the way of documentation so I am not so sure why I had this issue... but no worries.


I connected the iStreamer to my main stereo system in place of my Ayre C-5xeMP universal disc player using the Kondo Sound Labs KSL-LP interconnects and all that. I used an arrangement I've come up with for dealing with "walwarts"; specifically, I took an inexpensive audiophile-quality power cable (a Shunyata Venom 3) and a Conntek 30130 Male Plug Adapter IEC C14 To U.S. 3 Pin Female Connector that I purchased for $11.56 from Amazon, essentially creating an entry-level audiophile-quality extension cable. I may, at some point, have my various power cable adapters cryogenically treated; but for now they will do as is. I honestly don't remember what disc I started playing first from my iPad; it was probably track 1 ("Ruby") from Ali & Toumani by Ali Farka Touré and Toumani Diabaté on Nonesuch which, according to Amazon's ranking, appears to be a bestselling disc particularly in the world music category. I remember liking but not feeling terribly involved in the music; then I put on the 24/48 recording of Cara Dillon's Live At The Grand Opera House that I downloaded from the B&W Society of Sound. At that point, I started grooving. There was a much greater sense of depth, definition and musical involvement; and that has generally been my experience with digital music servers, that at 16/44.1, most CD players still do a better job at playing CD's but once you get to at 24/48, you begin to get some competition.

For my father's sake, let me explain what I mean by 16/44.1, 24/48, Etc. These numbers refer to the way the analog waveform that represents the music is converted into bits so it can be stored on a computer. So, metaphorically, think of the ocean and think of ripples in the tide; now imagine looking at those ripples sideways, as if in a cross section. You see peaks and valleys in all different shapes and sizes; to an all-analog system, that's what the music looks like. It's what you would see if you connected the output of your amplifier to an oscilloscope. Now imagine taking those peaks and valleys and slicing them up into lots of little pieces, then assigning a number to each piece representing it's height. You're obviously limited by two things: (a) the number of slices you have and (b) how big a number you can have. 0-10 just doesn't work. So the second number in the famous "16/44.1" is the sample, or frequency, at which numbers are assigned to the wave[form], specifically 44.1KHz or kilohertz, formerly known as "cycles per second". So on a regular CD, the music has been "dumbed down" to a rather paltry 44.1 thousand slices per second, the very minimum necessary to reach the hypothetical upper limit of human hearing (yes, Dad, even with your ears).

Now the first number represents the maximum size of the sample taken—or number assigned—to each of those slices. No, it's not 16 and 24; it's 65,535 (starting from 0, not 1, because you have to be able to assign a number to silence) and 16,777,215 because those are the largest numbers that 16 and 24 bits of storage can hold, respectively (a bit being a simple 0 or 1, the language of all computers). Pretty impressive difference, huh? So with a "24/48" file, you have a lot more slices and many more levels of resolution (horizontal versus vertical slices, looking at the tide, or wave[form] in a cross section) than in a "16/44.1" file, all of which leads to better sound. Simple, huh? OK, maybe next time I'll include a diagram. Getting back to the point at hand, even the most impressive DAC (Digital to Analog Converter) is limited by the amount of information in the music files it processes; so while it's not necessarily the case that a "24/48" sample file will sound better than a "16/44.1" sample file, all other things being equal, it generally does. As an example, I've been listening the Soundkeeper Recordings' Equinox by Markus Schwartz and Lakou Brooklyn at 24/96 through the Ayre QB-9 in my office system and it sounds great; but I can't wait for dCS and Sonicweld to upgrade their respective devices so I can listen to the 24/192 copy of this album in my main system. That will be totally awesome.

Apart from my dCS Debussy, against which the iStreamer performed admirably for its price, I had to have some point of reference to indicate whether the combination of an iPad, the iStreamer, and a pair of at least decent interconnects would be worth the price of admission. The first thing that came to mind was the simplest, truly least expensive "digital music server" I could consider, specifically my 64GB iPod Touch in the Apple universal dock driving the "TUNER" input of my Audio Note Meishu Phono Silver integrated amplifier via the Cardas iPod cable. Please remember that I plugged the Cardas mini plug into the line out socket on the back of the dock, not the headphone out of the "iTouch", which really would have placed it at a disadvantage, essentially creating a very small iPad with a line out rather than using an external DAC such as the iStreamer. I wish I could say there was a night and difference but—at least with 16/44.1 files (i. e., standard CD resolution files)—there really wasn't; again, it was when I got to the 24/44.1 and 24/48 materials on the iPad that the iStreamer really showed its stuff. If anything, the gently rolling frequency response of the Cardas iPod cable, made from the same wire as their Sennheiser headphone cables, made 16/44.1 material more listenable and you kind of had to play all 24-bit material on the iPad to make it worth the $199.95; although, had I been able to try the same Cardas cable as an ordinary interconnect rather than using the Kondo Sound Labs KSL-LP interconnects I normally use with the dCS Debussy, my conclusion might have been different. So suppose we try the ultimate reduction test; we take a really good LOD (Line Out Dock) for the iPad, bypassing the iStreamer and using the iPad's internal DAC with a cable that falls between the Cardas and the Kondo Sound Labs, such as a Moon Audio Silver Dragon LOD terminated with Cardas RCA connectors?

It just so happens that I have one of those. Thus returning to track 1 ("Ruby") from Ali & Toumani by Ali Farka Touré and Toumani Diabaté on Nonesuch, I would say we were finally cooking with gas. The sound was musical and engaging in a way that I had not heard from any iPod, iPhone or iPad going into my home stereo before and, most significantly, I wanted to continue listening to the music. So here I would say the cost of the iPad and the Moon Audio Silver Dragon RCA-terminated LOD was well worth the price of admission; again, for the uninitiated (Dad), the LOD or "Line Out Dock" and Apple's Universal Dock for the iPod do exactly the same thing; they give you a line out rather than a headphone out through to connect your iPod, iPhone or iPad into your home stereo relying on the internal DAC (Digital to Analog Converter, the thing that takes the 0's and 1's and reconstructs that ocean wave cross section we call music). The Silver Dragon LOD just does it better. This naturally led me to wonder if 24-bit material would sound improved through Apple's internal DAC, the answer being, "a little". So, once again, if your main goal is to start collecting 24-bit music, at a sample rate no higher than 48KHz, and you need something to store it on and a way of extracting the most music from those 16,777,216 levels per slice (0-16,777,215 being 16,777,216 unique levels), then the iStreamer is a very good value given a decent pair of interconnects; if, on the other hand, you mostly want to store 16/44.1—or lower resolution—material, then you're probably better off putting your money into the truly excellent Moon Audio RCA-terminated LOD and buying music.

In my passion to perform the ultimate test, I just had to try the following combination; and bear with me because it's a bit elaborate and modestly more expensive than anything else I've suggested:

Apple iPad → USB Type "A" Port from Apple iPad "Camera Kit" → Locus Design Polestar USB Cable Terminated with a Mini-B Connector (a smaller version of the standard type "B" connector) → iBasso D4 "Mamba" USB DAC and Headphone Amp Line Out → Cardas "iPod Cable" → Audio Note Meishu Phono Silver "TUNER" Input, Etc.

Now I have to confess we're getting into some special territory and it's just "tweaky" (esoteric, adjustable, capable of being fine-tuned) enough to appeal to the most ardent audiophile; plus, you can take the iBasso D4 "Mamba" in the field with you and drive your Ultrasone Edition 8 or Beyerdynamic T5p headphones. This is where I started to hear even 16/44.1 files take on depth and definition and lose a certain flatness of presentation; plus, the 24/48 copy of Cara Dillon's Live At The Grand Opera House had a delicacy and sense of palpability to it that I have not heard from a portable device before. The problem is that this is sort of a gateway drug, and the next thing you know you'll wind up with a 13" MacBook Pro sporting 8GB of a RAM, a 256GB SSD (Solid State Drive), a Sonicweld Diverter and the Rega DAC with all that that entails. On the other hand, it might just be enough to scratch the itch for a year and it's (almost) all portable, with the right pair of headphones. For what it's worth, I found the Eveready rechargeable 9-volt 175-mAh NiMH batteries to sound better than the average Duracell, by a significant margin.

One last experiment came to mind; specifically, use the iPad with the iStreamer and a pair of Moon Audio Silver Dragon interconnects—which I happen to have—to do a true side by side comparison between the iPad internal DAC and the iStreamer (which, if you haven't caught on by now, is an external DAC) given my use of the Silver Dragon LOD. I carefully disconnected the Silver Dragon interconnects from my Peachtree Audio iDecco's preamplifier output and the line in of the active Audioengine A5's I use in my bedroom system (where normally the Cardas iPod cable resides; the Silver Dragon interconnects are meant for greater things), then connected a system together as follows:

Apple iPad → HRT iStreamer → Moon Audio Silver Dragon Interconnects → Audio Note Meishu Phono Silver "TUNER" Input, Etc.

I queued up the 24/48 copy of Cara Dillon's Live At The Grand Opera House again and listened intently; this time, there was a sense of magic that I had not heard before from the iStreamer. Dillon's voice had depth and richness, the drums seemed finely tuned and taut and the bass thumped with authority. I heard the appropriate amount of air around the instruments but at the same time flourishes of detail emerged that I had not previously perceived, and everything held together in a really solid way. So maybe the Kondo Sound Labs interconnects were simply not the right match; the bottom line is that—with the right pair of interconnects—the Apple iPad and the HRT iStreamer can produce beautiful music together; so, yes, Virginia, there is a Santa Claus and this year maybe he'll bring you an iPad and an iStreamer with the appropriate pair of interconnects for your system. Now I need to go listen to the music.

Kindest regards,