AlanY

24/96 is one thing, but asynchronous mode transfers are the key thing to look for. There are actually three ways to transfer USB audio, but the asynchronous mode makes the most sense from the transport perspective, in that the receiver can apply its own clock, rather than having to derive a clock from the data coming in. If you have a DAC that is fairly immune to jitter, it doesn't really matter of course.

I wouldn't buy the Empirical Audio stuff. All he's doing is using a standard USB receiver with proper electrical termination. That was a rarity four years ago, but now everyone is doing it. You'll get exactly the same thing in a HagUSB, for $99 or whatever that sells for now. The guys who've written their own asynchronous USB stacks are worth paying extra money for though.

Assuming it's a solid state preamp (and this will work for many tube preamps as well), a y-splitter like other posters have suggested is your best option. It won't degrade the sounds because preamps are built for low output impedance and to drive relatively long lengths of cable.

I really like the selection of digital filters on the WM8741 though. That probably makes a bigger difference in sound than anything else at this performance level. But you're right, ease of implementation is huge in the DIY community.

If it actually has a 32-bit datapath (i.e. if that's not a gimmick and it doesn't truncate internally), then there's finally enough precision to use a digital volume control and ditch potentiometers completely. You can have 96dB of volume adjustment AND full 16-bit precision at the same time. (Incidentally, the Wolfson 8741 also allows this, but no one seems to care about that chip any more.)

Alas, there's no free lunch. Preserving phase ends up introducing pre-ringing, so each type is a trade-off. If you'd like some easy reading on the trade-off, these two references are accessible: http://www.wolfsonmicro.com/uploads/documents/en/Ultra_High_Performance_DAC_whitepaper.pdf http://www.ayre.com/pdf/Ayre_MP_White_Paper.pdf The Ayre approach is basically the same as filter 2 in the Lesso and Magrath paper.

What do you consider phase accurate? Linear phase? Minimum phase? Low group delay? Some form of apodizing filter?

Quite a few minor art films from the late 80s through mid-to-late-90s.

This is true, the analog stage and filtering scheme makes a big difference, but in some sense the PCM1704 will have a distinct sound from the subsequent crop of sigma-delta converters because it's a fundamentally different architecture. It's really the last of the R2R-inspired breed. It sounds like Currawong's ears are really sensitive to something it does right. If anyone's considering the PCM1704, the HagDac is another good option at $499. You have to put it in a box yourself though and add a PS, but other than that it comes preassembled. Haven't heard it myself, but it's not a bad value given that it also comes with the DF1704 and can be upgraded to a tube output stage.

I'm talking about conventional S/PDIF DACs, which the Neko DAC is an example of. Of course there are a variety of other custom solutions if you can eliminate S/PDIF or slave the transport.

The Descendents do indeed rock. You've got an awesome girl.

Yeah sure. Read the patent on the WM8804's elastic buffers. Every other off the shelf receiver uses a simple single or dual stage PLL that only filters jitter at high frequencies. The only other approach, steerable clocks, is generally not practical. It's WM8804 or ASRC if you're looking for an effective solution.

I think it's great that you're using the WM8804. That chip doesn't get used enough. It's pretty much the only serious alternative to ASRC for getting rid of jitter.

This is accurate. Usually zero is used. But you don't have to use zero, you can use any random number and you actually get the same result post-filter. One of the nifty counterintuitive results of digital signal processing. The main reason DACs use ASRC these days though is not for the fancy filtering, but to control jitter. That's the asynchronous part of "ASRC". Foobar resampling doesn't do this (it's synchronous resampling), but it doesn't need to either. To be useful for jitter control, ASRC must be done by the receiver.

That makes sense. The Stereophile review of the Medea says it has near-perfect 20 bit performance, so that would fit with the PCM1792.

Whoops, my mistake. PCM1702 is just 20 bit. Any guesses what that DAC might be?

Thanks for the link. That sticker is cheating Though judging from the DIP formfactor I think it has to be PCM1702. There aren't too many other options in the high end 24 bit category and DIP packaging. Interesting that they're just using dual PLLs to control jitter.

If you do a trial, be sure to post pictures of the internals. Curious to see what's in a pro DAC.

If you've heard two digital transports sound different, that's because of jitter (assuming both transports are bit-accurate and can read data off CDs properly, which is true in most cases). If you've heard two digital cables sound different, that's also because of jitter. There's really no other source of audible differences in digital circuits beyond data and timing. So most people have heard jitter, except for those to whom transports don't make any difference.

I'm sure it sounds fantastic, but the SDR-2000 Pro does use the PMD100 which is pretty old tech (1994). Hopefully the state of the art has moved forward in the last 15 years. (In terms of jitter removal it definitely has.) I think it's still worth giving the new device a listen. Firewire is always a good alternative to PCI Express cards for digital out. Unlike USB, Firewire is always an asynchronous protocol.

Dreadhead, you should add the Berkeley Audio Design Alpha DAC to your list. It's designed by the team who designed the Pacific Microsonics Model Two, which was certainly up there as one of the finest professional DACs in the world.

The new version of iTunes is indeed faster with large libraries, at least for me.

Anyone have any feedback on the RSP-2 stereo preamplifier? That looks like a sweet unit, and the proper bass management it has is something sorely lacking in other analog preamps.

If you're looking to learn about tube amps, Norman Crowhurst's Basic Audio series is exceptional. It has huge diagrams and illustrations on almost every page and is written towards a total beginner, but it's written so that you'll learn something too. Pete Millett says "If you're a beginner, READ THESE BOOKS!" You can download scans of the books here: Technical books online

That's insanely sweet. And it would solve the transport/iTunes thing.