iPad as a Streamer Into Benchmark DAC3

tmallin

WBF Technical Expert
May 19, 2010
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The iPad Pro (as well as some other, lower cost new iPads), has a USB-C connection these days. The largest capacity iPad currently available has 1 TB of storage on board, room enough for at least 1500 CDs. Such an iPad costs about $1,500. Some iPad Pro users have suggested using a general purpose iPad Pro as their streamer, saying there is no need to buy any dedicated music server--just hook your iPad Pro up to a USB-C connection whenever you want to listen to music through your system.

Such an iPad should be able to pass whatever digital audio signal you can access from a streaming service or have saved to disc on the iPad to your DAC, for example a Benchmark DAC3. According to tests, Apple has not dumbed down the iPad's USB-C output and it can thus pass bit--perfect data even from high resolution digital files. If you have, for example, a Benchmark DAC, the Benchmark's front panel display should tell you the resolution of the signal it is receiving from any program. If the lights indicate it is receiving the full resolution of the source you are sending, the iPad Pro should work at least reasonably well as a music streaming device.

Apple's AirPlay is limited to 16/44, for example, so any attempt to output higher resolution gets downsampled to that resolution. I know the old Apple Airport Express digital output (the combination stereo miniplug/optical digital jack) was also limited to 16/44 resolution. That was actually better sounding than the Apple TV units which altered everything to 16/48.

Certainly there is nothing "wrong" with using an iPad Pro as your music source. You could, of course, try A/Bing it against a "real" music player/streamer. Perhaps you could borrow a good dedicated streamer from a dealer or friend for a couple of days and try experimenting with both high and low resolution content. If you can't hear any difference, or if any difference you hear is either sonically insignificant or not clearly better or worse, just different, then the iPad Pro may well be a fine solution.

I use a late model iPad Pro in my system as a controller for my Lumin X1. I can also play tunes from it via AirPlay to the Lumin. I do not have it wired to the system with USB or other cabling.

One reason for going beyond the iPad Pro as a music streamer is if you want to use Roon. Roon requires a "real" computer as the Roon Core from which the music is sourced. An iPad Pro cannot be used as a Roon Core. In my system my iPad Pro controls a Roon Nucleus+ which does the streaming either from online services or a 1 TB USB stick plugged into the back of the Nucleus+. The Nucleus+ is a stripped down high performance computer dedicated solely to music serving.

A USB-connected iPad as the music source is one thing I have not tried. I've simplified my system to such an extent that I no longer have a USB digital signal pathway to my amps. My current Dutch & Dutch 8c speakers don't allow me to drive the amps in the speakers from a USB connection. I'd need some sort of USB to SPDIF conversion.

Roon aside, I certainly agree that if I could have only one streaming service, Qobuz would be it. Spotify has the most albums of any streaming service but as yet is not even CD quality. Qobuz is deeper in the classical and jazz catalogs than Tidal, whereas Tidal is much deeper into genres in which I have little interest. The Qobuz Hi Res albums usually are at least as good sounding as Tidal's MQA version (although they frequently sound quite different) and eliminate the need for software or hardware which will decode/unfold MQA. The Benchmark DACs, for all their merit, do not do MQA, so Qobuz is clearly your best choice for a high resolution streaming service if you don't have a means for decoding MQA files.

The Benchmark DAC3 units are indeed superb for PCM digital playback up to 24/192. I use a Benchmark DAC3B for my electrostatic headphone system to drive Stax SR009S headphones via a Mjolnir amp and this is the best sounding headphone set-up I've ever owned.

As to the comparative quality of metadata of Qobuz vs. Roon, I'm not sure why some might find Qobuz to be superior. Do they like the album reviews better on Qobuz? Qobuz does seem to link to all the albums on a particular label, which Roon does not do well. Or maybe they like the way Qobuz categorizes music into subgenres better than Roon does. But those are not the metadata most people are interested in. For example, look at the credits for any randomly selected album and how many of the people or groups named are links to their other work--very few on Qobuz, most on Roon. Also, Roon integrates your own music files into a unified library with your Qobuz and Tidal favorites which Qobuz on its own cannot do, of course.

I think many people prefer to have the overlay of the streaming software used by dedicated streamers to that of the native Qobuz software. For example, many folks really like the way the Lumin app organizes things; the same goes for BlueSound and especially for Roon. This software overlay is something you don't get with just native playback of Qobuz on an iPad.

And some streamers, like the Lumin U1 Mini I previously owned and the X1 I now own, allow upsampling/resampling, decode MQA, and handle native DSD files with aplomb. The iPad doesn't do those things, at least not without addition of apps. But, I agree that, at the end of the day, none of those are really needed once you have a streaming service of Qobuz quality. I think most music sounds most natural when not upsampled/resampled, MQA is only different not really better than Qobuz's high res files, DSD resampling is, again, at best just different sounding, not better, and the number of native DSD recordings is miniscule.

Years ago I used an Apple Airport Express (about $150 at its peak price, as I recall) as my main streaming device. I've used various iPhones and iPads as streamers as well, just never via a USB output. I've also used dirt cheap streamers such as Chromecast Audio. They all work and sound quite good. I've also now owned and used a number of other more expensive streamers from Logitech (Squeezebox Touch), BlueSound, Auralic, and now Lumin. They may all be bit-perfect, but if we thought that was all that mattered sonically, then the very first Sony CD player would truly have provided Perfect Sound Forever.

I'm not saying my Lumin X1 streamer is worth its $15k price compared to a "free" streamer like the iPad Pro's USB-C output. But then you don't really know how good your iPad sounds as a streamer unless you compare it in your system to a dedicated music streamer with a good reputation.

Why anyone would buy a $15k music streamer is a very good question since no one would argue that $15k will make anywhere nearly as large a difference in your sonic reproduction quality as $15k invested in good speakers (e.g., the cost of the Larsen 9s) versus el cheapo $39.95 speakers. An iPad Pro used as a streamer and also for other personal use is basically "free" and surely works quite well enough sonically to make a fine sounding audio front-end even with $15k speakers like the Larsons.

I think most here would agree that speakers, rooms, system set-up (primarily the positioning of speakers and listener) and room treatments are the most important elements of home audio in terms of sonic results. Room treatments can cost a bit, but most are not super expensive. The room, unless you are building one from scratch to create a reflection-free zone like the one REG talks about, is just a matter of what you have available to work with, given your circumstances and judgement. Set up is also either free or inexpensive, just time consuming to get right. Speakers are thus the big-bang-for-the-buck element. Even I agree with that.

All the electronics, cabling, powerline quality, etc. are less sonically important to the final result. While changes may well be audible, they are not as obvious and thus probably not as important to your enjoyment.

It is indeed one of the wonders of our current age that a streaming audio front end can be basically free these days (except for the cost of the streaming service) and sound quite fine even when paired with the finest speakers. Surely any sonic differences among streaming front ends do not remotely approach the sonic differences between a child's $39.95 phonograph and a high-end turntable/tonearm/cartridge properly mounted for vibrational isolation, something which can easily cost many tens of thousands of dollars these days. Most of the mechanical factors are eliminated with streaming, program material is about as broad, and convenience is overwhelmingly superior.






 

tmallin

WBF Technical Expert
May 19, 2010
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[Continued from above]

I certainly understand reluctance to even make a comparison between a "free" iPad streamer and a purpose-built music streamer. If you are satisfied with the sound of your basically "free" streamer, why bother? And if you haven't previously heard any differences in digital sources feeding your, for example, Benchmark DAC3, why would you now hear differences? But here is my different perspective on the DAC3.

I've owned three versions of the Benchmark DAC3: the HGC, DX, and B. I still own the B. Yes, the DAC3 is as excellent a DAC as any I've heard. That's why I've owned three versions and still own one. But the HGC version sounds clearly better than the DX and the B sounds best of all. I could understand if you don't know about these sonic differences since most people have never heard more than one version of the DAC3, much less owned all three with overlap and the opportunity to compare their sonics. There are reasons for these sonic differences. The DX uses only three paralleled sections of its ESS 9028 chips for its main output, while the HGC uses four. In the B, unlike the other two versions, the power supply does not have to drive any headphone output and there is no volume control, analog or digital, in the sonic path.

I don't care what Benchmark's published measurements purport to prove, to my ears the differences in what is feeding the Benchmark DAC3 are easily heard. I do think the Benchmark DAC3 is more immune to such differences than most other DACs, but it is not audibly immune--not hardly. What are instantly audible and important differences with most DACs become just sonically significant differences. Not only are the sources upstream rather obviously sonically distinguishable, but the USB (or SPDIF or Toslink) cables feeding the DAC3 from any given source make readily discernible sonic quality differences.

In my computer desktop electrostatic headphone system, the USB out of my Dell all-in-one computer feeds the DAC3B via one meter of USB cable. Downstream from the Benchmark is the Mjolnir Audio KGSSHV amp and Stax SR009S headphones. I can hear the difference in sound when changing the audio sampling of any given audio program in the computer from 16/44, to 24/44, 24/96, 24/88, and 24/192 via the computer's sound settings. This is despite Benchmark's claim to automatically internally upsample all inputs to 211 kHz. I can hear changing the computer's audio driver from Waves Maxx to Microsoft HD. I can even more clearly hear the change in the single USB cable from Belkin, to Oyaide, to Triode Wire Labs, or whatever. I can also clearly hear the sonic differences among different USB output jacks of the Dell computer.

So, yes, since the Benchmark DAC3 sonic output quality is affected by such changes it will certainly reveal any sonic differences between streaming from an iPad Pro via USB-C to streaming via USB from, for example a Lumin U1 Mini ($2,000) via USB. I was not suggesting eliminating the Benchmark or comparing the Benchmark to any other DAC, just comparing the iPad Pro as a streaming source with a purpose-made audio streamer--the Lumin, for example, with both feeding the Benchmark DAC3.


I'll take a stab at defining "better" sound in the context of DACs. Compared to analog sound, things that are sonically "wrong" about DACs, and really all things digital, have from the beginning included:

  • brittleness and/or grunge in the upper frequencies
  • a feeling of tension to the sound, in contrast to the relaxed (even if frequency response colored) sound of analog sources
  • lack of clarity in terms of hearing small midrange details without unnatural high frequency brightness
  • compression of depth and other aspects of soundstage size so that the presentation sounds small and flat rather than open, spacious, and enveloping
  • a "crunch" of loud transients and especially loud high frequency transients--a momentary blast of nasty distortion
  • a lack of "blackness" to what should be background silence--a perception of noise-filled spaces even when no hiss or other noise is actually audible
  • on the other hand, a covering up of small noises in the background, such as chairs squeaking, air-handling noise in the recording venue, subway noises, breathing of the artists, etc.
  • unnatural cymbal strike and shimmer sound, tending to make these sounds more like the sound of steam periodically escaping from a pipe valve
  • a general feeling of the presence of distortion of some kind despite low measured distortion
  • a lack of low-level detail in quiet portions and the unnaturally fast fade to black during the reverb tails of music

To the extent that these problems or "digital artifacts" are lessened, a DAC or other digital component sounds "better," that is, more natural and more like an analog feed from microphones or the way music sounds when it is not amplified and not heard through any electronic devices at all. As time went on, DACs and digital sound generally had less and less of these problems.

These problems tend to make for "annoying" sound rather than the "colored" sound problems which are typical of analog sound system problems which rather clearly originate from frequency response problems. We all can appreciate the relative flatness of digital media and equipment in terms of frequency response, but I think we all can remember just how annoying early digital sound was because of the combination of the factors listed above.

While some may feel that the Benchmark DAC1 already reduced these problems to near zero, comparison to later versions of the Benchmark DAC while listening for such problems will reveal how the later versions and even different versions of the DAC3 sound even "better" in some or all these ways. Yes, the original Benchmark was better than most other DACs of its time in these ways, but many listeners heard an unnatural brightness and a bit of brittleness, at least. The DAC3 versions are all quite superior in most of the areas mentioned above, and some are "more better" than others.

While many of these factors are a bit easier to hear on headphones than speakers, good speakers work fine to reveal such differences once one is "tuned in" to what to listen for. For example, the difference between the DAC3 HGC and DAC3B was immediately apparent through my Harbeth M40.2 speakers when I put those units in front of the Benchmark HPA4, using only the HPA4 to control system volume in both cases.


I'm not saying that the iPad Pro will not fare well in comparison to a purpose-built music streamer. Many computer audiophiles feel that Apple front ends sound better than Windows computers, for example. Many seem to favor Macs. But then I've read reviews by Macbook Pro users finding that this or that dedicated audio streamer sonically bested their beloved Mac. I haven't yet heard of much use of the iPad Pro as an audio streamer in a good audio system and thus I'd be interested in anyone's comparisons of it to a purpose-made audio streamer.
 

tmallin

WBF Technical Expert
May 19, 2010
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My favorite USB cable in terms of sound is this one, a joint project of Triode Wire Labs and P. I. Audio Group: https://triodewirelabs.com/product/discrete-usb-cable/ Yes, it's expensive, but not crazy nutty expensive like some I've owned or tried in the past. I'll defer comment on whether it has "accurate sound," but just say that I really like its tonal balance and solid bass end, clarity, and spaciousness when heard through my computer-based electrostatic headphone system. My Stax SR 009S electrostatics react well to the bit of extra warmth and bass oomph this USB cable has. It connects my computer to the Benchmark DAC3B. It also worked well in my audio room when I was using Benchmark DAC3 units there. But it's probably too expensive and too stiff to work well to connect an iPad to your system for streaming if you want the iPad at your listening seat. You don't want to flex stiff USB cables much since many of the plugs and jacks don't fit very snugly.

I've eliminated USB audio connections from my audio room now with the D&D 8c speakers. USB connections usually sound very clear but that clarity is at least partially tied to a too-bright presentation and compared to SPDIF cables have less "there there" as one Stereophile reviewer used to say. USB cables are all over the map tonally; swapping one for another frequently is an unintentional tone control event.
 

matthias

Well-Known Member
Mar 14, 2019
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@tmallin

very interesting thread :)

I am curious if you tried any USB cables with USB-C connectors.
If yes, did you found good sounding ones?
Thanks

Matt
 

tmallin

WBF Technical Expert
May 19, 2010
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I have no opinion as to the sonics of USB-C connections. The only USB-C cable I use in an audio system is a two-meter Apple cable connecting my iPad Pro to its Apple wall-wart power supply to keep that iPad charged up as a control device for my audio system. When I play music from that iPad into my audio system I do it via AirPlay/Lumin Streaming, not via a wired connection. I also disconnect that iPad from the USB cable when using it at all to control the system or play music through it. It is thus operating/playing on battery power and not the AC electrical system powering the rest of the components in my audio room.

I do like USB-C for its easy plug-in; you don't have to worry about which side of the plug is "up." Apparently these cables also work better with higher capacity chargers, allowing quicker charging of the larger batteries in iPads and Apple computers.
 

matthias

Well-Known Member
Mar 14, 2019
372
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Germany
@tmallin
thanks.

I asked because all new MacBook Pros and iPads are equipped with USB-C outputs.
The upcoming ARM based Macs seem to get very good USB controllers from ASMedia, so it would make even more sense to use them as servers up to a certain SQ level.

I think it is a pity that some very good USB cable manufacturers refuse to offer their cables with USB-C connectors.

Matt
 
Last edited:

Alrainbow

Well-Known Member
Dec 12, 2013
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I used I pads , iPhones years ago yes it’s good but I’m sorry not in the universe of a good serve. perhaps try a loaner well made server then compare.
 

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