kdoot

"Bit Perfect" just means you didn't change anything between reading the audio file and sending its data on to the DAC. If you change the sample rate, or the volume level (in software), then you've... changed something. And that's not bit perfect.

Bit perfect can be important, yes, but it's completely independent of integer mode. You can use Audirvana's software features such as upsampling or volume control to create an audio stream which is NOT bit perfect but which IS passing data from the application to the USB interface in integer mode.

That's fine and all... but it's a powerful thing to have some understanding of what "integer mode" actually is and how and why it can affect the sound quality. Are you aware that all SPDIF PCM data transmission uses integers, 100% of the time? Or that 24-bit integers such as we use for PCM audio samples are able to be conveyed with absolutely perfect accuracy inside a 32-bit floating point data format and then retrieved again? The point of "integer mode" is merely to reduce the number of conversions between integer and floating point formats. Not because these conversions damage the data (they don't) but because the act of converting involves an electrical action in a circuit somewhere which can influence the behaviour of other parts of the system by tiny amounts. So for "integer mode" to be beneficial, you have to have a system whose performance is being audibly degraded by these tiny machinations. Most of the time, and especially in the sub-$1000 bracket, there are plenty of other factors which make a bigger contribution to the overall performance than this. The right choice of USB interface can make integer mode irrelevant. The Audiophilleo 2 is a great example: it supports integer mode but it sounds consistently excellent whether you send it integers or floats. It does a great job of isolating the DAC from the foibles of USB. Partner something like that (especially a 2nd-hand one if you can find it) with an inexpensive but well-designed SPDIF-only DAC and you're off and running with quality computer audio.

Honestly, with a thousand dollars to spend, I'd suggest that you shouldn't worry yourself about Integer Mode compatibility. Many other factors will be much more significant in determining how you enjoy the sound of a DAC. Don't do optical at that price point. You want something which the computer sees as USB. Either buy a DAC which has a reputation for being awesome with its built-in USB, or buy as good a USB-to-SPDIF (coax) converter as you can manage along with a DAC known for sounding awesome with a good SPDIF "transport". The vast majority of DACs in the above categories will support 24/192 anyway. So you just have to look at whether they have the other features you care about (eg balanced and single-ended outputs) and try to audition a couple to "get your ears in", after which what you read other people write about the sound of different DACs will convey a bit more meaning. Try reading some of John Darko's DAC reviews at digitalaudioreview.net - he likes to emphasise the under-$1000 options.

Those Sharp modules appear to be unavailable for sale in the USA. Is there some kind of intellectual property problem with Toslink clones over there? Can you point to any other options? Also since I'm posting can I ask whether the TORX1701(F) would work as a general purpose consumer audio receiver, or is its "minimum" 20Mbps signal rate an actual minimum below which it won't work? Thanks!

Yes, bits are bits. And hi-fi DACs are devices which attempt to turn those bits into an accurate analog representation with mind-boggling accuracy in terms of microvolts and perhaps even nanoseconds. As such, they tend to be vulnerable to "noise" (volts) and "jitter" (timing variations) resulting from their connection to the transport which is feeding them their data. Toslink clearly doesn't have electrical noise problems, but it can be pretty challenging in terms of jitter. If you ever want to hear what jitter sounds like, compare a cheap toslink source into a typical DAC - especially from about 3-5 years ago, with the Wolfson 8804/5 or CS logic SPDIF receivers - with a really high quality coax source into the same DAC. Send the same bits. They won't have the same "quality" at the output. More sophisticated DAC designs are starting to overcome this problem, to the point where my preferred input on my new DAC is in fact the Toslink one. That's a great question. My first reaction: HDMI, USB and network streaming.

Metrum Octave mk 1, driven by Audiophilleo 2 with PurePower. I was doing 2x/4x upsampling on the Mac mini using the iZotope SRC in Audirvana.

DirectStream DAC... Listened in the showroom. Listened in my own room. Bought it. Lovin it.

There's been a related discussion over at the PS Audio forums, in the DirectStream DAC section. I've just bought a new DAC and one of the things I love the most about it is its Toslink input. PS Audio only guarantees up to 96kHz on that input, but some units just happen to be OK all the way to 192kHz. Happily, mine is one of those. As for the sound quality of toslink, I agree with Miska *in principle* that an ideal DAC should care about nothing but the bits. I also agree with others that *in practice* many DACs have struggled to sound good with Toslink - which I believe is due to the difficulty of extracting a clean clock from a toslink signal. While toslink is totally immune to electrical noise, the jitter is severe, and most DAC designs fare much better with the sharp transitions possible on coax yielding a more consistent clock. I'm trying not to sound too much like a sales pitch, so I'll just add that my new DAC sounds awesome via optical and leave it at that.

Something like "IF input is in DSD128 format AND volume is 100 THEN pass input directly to output"?

Al, some people *like* the sound produced by a more jittery transport. I've been in A/B comparisons with a couple of them. One said that there was more "flow" to the music with the CD transport than with the computer/Audiophilleo combination. I don't understand it, but I'm OK with it. To each their own.

One benefit of a product like the Audiophilleo is that it makes the downstream DAC far less sensitive to your choice of computer, software, USB cable etc. It may well be that a DAC's built-in USB interface can deliver superb results, but can it do so without requiring complicated tweaks or expensive cables? The answer will naturally be that it depends on the DAC. The better and more expensive the DAC, the less benefit you'd generally expect to see from a high quality external USB-to-SPDIF converter. But YMMV.

Oh, sorry - context switch. First and foremost, I have Apple gear rather than Windows or Android... so DLNA is not a great fit for me. The other key strengths of the bridge (ie the clean power and the digital lens) look like being far less relevant given the design of the DS DAC. Today I use a Mac mini with Audirvana and an Audiophilleo as my high-fidelity transport. If the DS DAC's USB input is really great, I'd use that. If not, I could keep using the Audiophilleo on coax. Any other "streaming" source such as AirPort Express is for convenience only and I'm willing to sacrifice a touch of quality, so any of the Toslink, coax or AES/EBU inputs could be used. And then I'd have to figure out the best way to get my Blu-ray, Apple TV and broadcast TV routed into the DAC as well in the absence of HDMI.

Not quite. My interest is in video playback with highest-quality audio, and in SACD playback with native DSD. The copy protection rules for Blu-ray and SACD prohibit the output of their best quality audio data over an unencrypted digital interface such as I2S. Happy to purchase. Not happy about the limited catalog. I can buy loads more content on physical media, but then I need a great playback solution - potentially something like what I've suggested. HDMI offers convenient access to the high resolution PCM and native DSD audio from DVD, Blu-ray and SACD discs, and best-possible audio reproduction while watching movies or concert videos.

The simplistic answer is probably "economies of scale". No, the NAD M51 and also the C390DD with HDMI expansion card will play any PCM audio streams they detect on the HDMI input.