Audiophilleo1 USB-S/PDIF converter processor... who's trying it?

Just finished a detailed review which is posted in the 32 ohm section of http://www.6moons.com/audioreviews/audiophilleo/1.html  with additional information in the review of the Wilson Sashas http://www.6moons.com/audioreviews/wilson/1.html 

I'll be happy to answer any questions were, as 6moons doesn't have a forum or comments section.

Some of the interesting mods that have cropped up for the hiFace in-line device are certainly beneficial. However, the scope of the two products is completely different, and the Audiophilleo design inherently doesn't have, or already addresses the issues that modders are trying to fix as after-market improvements.

The Audiophilleo1 model, which has the display, includes several digital preamplifier feature, such as a noise-shaped digital attentuator, a balance control, ramped up/down muting, absolute polarity control (some tracks have the polarity reversed) and so forth. It also has a remote control receiver.

The Evo (should have a production unit here tomorrow) is extremely versatile with respect to inputs and outputs. Sound quality I heard from a prototype was certainly very good, and the connectivity is excellent.

The Audiophilleo 2 is USB in, S/PDIF on BNC out. It runs on all OS, including iOS, using the native USB driver (Windows Vista/7 need a custom driver but only for 176 and 192). It can also plug directly into the DAC without a cable, which saves money and may improve sound quality.

The difference may be between very good and very, very good. They're about the same price.

Geez, what beautiful ears you have!

My opinion is that the very low jitter is the most important feature with respect to overall sonic improvement. And yes, the Audiophilleo2 will be identical to the Audiophilleo1 in this regard. The dithered attenuator in the AP1, compared to those in other products, is a matter of refinement and possibly taste. As mentioned, it's subtle.

As you may know, there are several established methods for doing software attenuation, and the Weiss DAC 202 has a combination of analog and software dithering. It may do things a little differently than the Weiss INT 202.

The Berkeley Audio Device is, I believe, software only, as is the Audiophilleo. Spectral preamps use motorized analogue in some cases.Naturally, one big plus of software attentuation is that it doesn't wear out, and maintaining linearity and left/right tracking is easier.

All these designers know what they're doing, and it's unlikely that one would be unhappy with any of their solutions.

There two things to consider.

Firstly, jitter relates to clock stability, and highly-specialized clock measurement gear, followed by software analysis of the measurements to get an integrated phase noise value, over a given spectrum, is required. 10 pS of jitter is nothing that one could see on an ordinary 'scope or even measure reliably with, say, an AP SYS2722 which is a more general-purpose (and of course excellent) analyzer.

Secondly, the Audiophilleo1 allows for adjustable risetime in the edges of the S/PDIF output in 5 steps, from 700 picoseconds to a relatively leisurely 15 nanoseconds. Once again, these values are nothing that could be seen easily on most 'scopes. This feature is designed to optimize performance with a wide range of DACs, whose input stage may prefer a particular risetime.

So to answer your question more directly, the quality of the output from a S/PDIF source with very low jitter and a well-designed output stage that allows variable rise-time is hard to evaluate reliably by eyeballing it on a 'scope. The fidelity of the waveforms being tested is greater than anything the 'scope could differentiate. While it's fun and instructive to post graphics of the S/PDIF 'eye pattern' measured using an AP SYS2722, the noise levels of such test instruments are similar to or worse than those of the device under test in this case. Sure, grosser issues will be apparent, but then, they'd also be apparent to your ears.

In the end, go by what you hear. My observation is that you can pretty readily sort S/PDIF converters into various categories, such as less than 100 ps jitter (the best ones); 100 ps to less than, say, 500 ps (OK, but clearly not as good as the first category) and then the 500-1000 ps and up category (really bad news, and typical for comes out of many computers and consumer electronics devices).

@endless402 The Evo is in house, as mentioned, and it sounds quite nicely, based upon a very quick listen at 44.1. Could you share a link to RASTME? It doesn't seem to show up in search.

@nada... glad to hear that we share the same experiences about the efficacy of using our ears, although possibly your picture just might suggest that is the case :)... regarding the jitter-bug database, well, the usual gear as mentioned may not really be that usable for evaluating the best products, and it's very costly. You need specialized clock jitter measurement devices, rather than spectrum analyzers. The main thing is that very few USB-S/PDIF converter/processor manufacturers publish any jitter numbers at all! and this is the key criterion for evaluating their performance. That third-parties have to do this testing on their own is not a good sign :)