Osoraku Nakamori

Hi Chris,<br /> <br /> Ahh, I see. I didn't fully understand your setup. I agree the Amarra behavior and HDCD observation indicate native resolution streaming. That's excellent! Thanks very much! <br /> <br /> With this issue answered, my plans now are to use a Mac Mini as a transport, which will pull from my Mac Pro "server". Perhaps I'll also use some local storage or external firewire hard drive. Then I'll work on improving the jittery toslink connection from the mini to my Wadia DAC. I hoping Wadia comes out soon with their rumored 27ix upgrade which will add a USB input. But I've also heard that it won't support 88.2 or 192 kHz, only up to 24 bit, at 44.1, 48, or 96 kHz. Shame since I already have a fair amount of 24/88.2 and 24/192 material. Perhaps I'll have to seriously consider replacing the Wadia (<gasp!>) with a newer piece. <br /> <br /> Thanks again for this terrific site and your help with my question!

Hi Chris,<br /> <br /> Yes, I understand exactly what you are saying, and you are not wrong concerning Audio Midi setup and iTunes interaction. But I think I am not being very clear in my description. <br /> <br /> We want to establish that high resolution content is being streamed wirelessly at its native resolution. The evidence we have so far (IMHO) does not allow us to conclude that this is necessarily the case. It might be the case, but we cannot say for sure. <br /> <br /> Why? Because currently the only way we have of determining what the resolution of streaming content is is to look at the DAC display. But we know that the DAC display <i>always</i> says "24/96" if you have Audio Midi set to 24/96 on the remote Mac (the one feeding the DAC), <i>even if the track being sent from the server (Mac Pro) is really only 16/44.1. </i> So we can't claim that the streaming sample rate as determined by the DAC display always necessarily represents the streaming rate over the WiFi. For example, maybe a 24/96 track is being sent from the server to the remote Mac at a down-sampled 16/44.1 rate, then because the remote is set to 24/96, the stream is (re-) converted to a (now fake) 24/96 and therefore shows up at the DAC at 24/96. The DAC has no way of knowing if the stream was 24/96 all the way from the server, or if it underwent an arbitrary number of rate shifts along the way, with the last rate shift before reaching the DAC setting the stream to 24/96. And the critical point is that any downshifts in the streaming resolution anywhere along the chain, even if followed by "upshifts" before reaching the DAC, will cause loss of information, and loss of true resolution.

Hi Chris,<br /> <br /> Thanks! Actually, this is what I observed on my system as well (except for the HDCD part). But I'm curious ... leave your system exactly the same way (with Audio Midi Setup on MacBook Pro set to 24/96). But this time, select a 16/44.1 track on the Mac Pro for streaming/playback. What does your DAC indicate now? I'm guessing it still says 24/96. So therefore, we can't really tell if the Mac Pro is streaming the full res file, or (possibly) downsampling/down-converting it first. The reason I am suspicious is we know that the Mac Pro performs down-conversion if it is streaming to an AE or an Apple TV. How do we know it streams at the track's full native resolution if it is streaming to another Mac instead of the AE/Apple TV? I think the only way to really tell, as I mentioned previously, is perform some kind of more intricate data comparison. What do you think?<br /> <br /> Thanks.

Does anybody know which DAC chip the QB-9 uses? I know the USB streaming is handled by the TI TAS1020B, but which DAC does the actual conversion? Just wondering. I realize that the real magic of the QB-9 is not really which DAC chip is employed, but mostly the superior way USB is handled and the superior analog circuitry post-DAC.

Hi Chris,<br /> <br /> That would be terrific! Just curious, how are you going to measure? I imagine you have to some how compare the data at the toslink output of the MacBook Pro with the data in the original hi-res file? Or perhaps a slightly less direct, but perhaps easier comparison, is to compare the data at the toslink output when a hi-res file is a) streamed from a host (Mac Pro) over WiFi and b) when the same file is played directly from the MacBook Pro's hard drive. <br /> <br /> I'll be interested to hear the outcome! <br /> <br /> Thanks.

Hi Chris,<br /> <br /> What a wonderful site! Thanks very much.<br /> <br /> I've been playing with computer hi-fi for about a year now. I have recently re-ripped my entire CD collection in Apple Lossless, have been purchasing online 24/88.2, 24/96, and 24/192 content from Linn, HDTracks, etc. <br /> <br /> I have used the Airport Express with mini-toslink out to the DAC in my main system (a Wadia 27ix). As is well known, the output of the AE is limited to 16/44.1, and I understand the Apple TV has the same limitation. In order to get around this limitation for wireless streaming, I have experimented with my MacBook Pro in place of the AE. Now if I play a hi-resolution track from a shared iTunes library on my main computer (Mac Pro 2 X Dual Core 3GHz), and having correctly set Audio Midi Setup on the MacBook Pro to match the source file, I can wirelessly distribute hi-resolution music from my main computer to my high-end audio system, and have the files played at their native resolution. (However, I think the S/PDIF Toslink is limited to 24/96, and my 2006 vintage MacBook Pro doesn't seem to offer 88.2 KHz sampling rate). <br /> <br /> Here is my question: How do we know that the hi-resolution file is being faithfully distributed to the remote machine in its native format? Yes, my Wadia <i>claims</i> it sees 24/96, for example, but this will be true simply because of the Audi Midi settings on the remote machine. Playing 16/44.1 tracks in the same way with the same Audio Midi setup also results in a 96KHz signal to the DAC. I've tried to verify the operation by looking at Apple's documentation and forums, googling, etc, but haven't come up with an answer. In short, does Air Tunes (I think that's what Apple calls its wireless distribution component) handle hi-resolution files at their native resolution, without sample rate conversion? <br /> <br /> One sure-fire approach would be to actually duplicate the track(s) themselves on the remote machine, but that of course has its own issues (size) and defeats the goal of wireless streaming from a main server.<br /> <br /> Does anyone have any insight into this question? <br /> <br /> Thanks! <br /> <br />