Guys, got a response back from Channel D. Understandably, they are very busy and participating here would be tough, but they (Rob Robinson, specifically) did send me a REALLY nice and helpful response. Here it is:
Thanks for the heads-up on the thread, and the invitation to post. As you probably know, it can be very time consuming to contribute to Internet forums and then monitor and respond to follow up posts. However, you can post this response, if you like.
Questions directed to the Channel D support email address found on Channel D website are answered as quickly as possible, and telephone support also is available. Just to clarify some of the issues raised in the thread, however (of course, most if not all of this information can be found in the complete documentation included with Pure Vinyl (the 2.3 application suite) and the Pure Vinyl 3 Preview Release, as well as on our website):
Any dual core Intel Mac Mini has more than enough grunt to handle 192 kHz with Pure Vinyl. That sample rate is recommended, because the RIAA correction is improved compared to lower sample rates (the signal is more "analog-like").
RAM is not an issue, the stock 1 - 2 GB is sufficient, unless, as pointed out, wanting to use the Memory Play feature of the iTunes Music Server, where at least 4 GB of RAM is beneficial. It is do-able even on older machines; an older PowerPC G4 or G5 also can be used, but at 192 kHz, system setup and optimization become more important. As for an Apple TV, that is not a good choice, too limiting (for a music server, that is; can't be used with Pure Vinyl at all). A Mac Mini can do all that an Apple TV can, and more. Besides high resolution digital audio (and phono, with Pure Vinyl): home theater setup with widescreen 1080p HDTV, Netflix streaming video, terrestrial or cable HDTV reception (with a $100 dongle), DVD player? Capably handles all of that (except for Blu-ray, but that's another story; need a separate player)... and the wireless mouse and keyboard are a very capable remote.
For storage, a USB2 pocket drive or NAS are sufficient, speed is not an issue here.
Additional gain will be required besides a MC step-up transformer, can't simply go into line inputs. I believe the enjoythemusic review used additional analog gain available on the computer's audio input, and even then might not have been close to digital full scale input. I think it says a lot that the quality was as good as reported, without even being close to having the optimum setup.
As far as recommending equipment... that is strictly determined by personal budget. If you can afford more expensive preamps or audio interfaces, they will deliver noticeably better performance. It would be nice if the optimum sound quality could be engineered at a low price point, but it is not practical to address all the issues while keeping the price low. The Fireface 400 is a nice, solid, high-value, all-in-one solution for using a low output MC cartridge and supporting 192 kHz, and is one of the few interfaces that also has a balanced high impedance input suitable for MM cartridges. A Lynx Aurora (with Firewire card) or L22/LynxTWO (in a Mac G4 or G5 tower, or Intel tower with an expensive Magma PCI adaptor) combined with our Seta Model L or H phono preamp is noticeably better sounding, but also considerably more expensive. But keep in mind that most of the improvement in sound quality (compared to a standard phono preamp) is due to the RIAA correction in software (presuming a capable gain stage / preamp, which includes the Fireface above and several others), and the additional improvement from having more expensive audio interface hardware, while surely noticeable, is somewhat less by comparison. Diminishing returns applies.
Here is a list of "sound cards" (to use that term loosely):http://www.channld.com/soundcards1.html
Besides the above list, the software is designed to work with any Mac compatible interface. Bear in mind that there are many more options out there, and it is probably impractical to test them all.
Note that it's also possible to have more than a two-way crossover with Pure Vinyl / Pure Music, by using the AudioUnit plug-ins in conjunction with the built-in crossover. The built-in crossover uses 64 bit internal precision, however, compared to 32 bit for the plug-ins. The capability of the built-in crossover will be expanded in the near future, as will the flexibility of handling multiple inputs, used with a multichannel input ADC, as a virtual line stage preamp with multiple selectable input sources. All of this stuff will then be accomplished tidily in one application.
Support is an important issue when considering introducing a product on the Windows platform. The number of possible system configurations is greatly multiplied. For less technically savvy users, a company would then have to serve as front line support for Windows, in addition to its own products. So rather than divert resources to that platform for the sake of a larger market, better to focus all effort on the Mac platform and deliver really great products taking advantage of all that platform has to offer. Other companies also choose to focus only on the Mac; and some have even dropped Windows, for instance, Apogee.
I hope this is helpful and not too long of an answer.
Channel D Support"
The crossover stuff, in particular, has me very intrigued. Really cool stuff!