The following information was taking from the Reference Recordings website.
http://www.referencerecordings.com
HRx is a trade name for high resolution audio WAV files on a DVD-R data disc. These files contain exact bit-for-bit copies of Reference Recordings’ master recordings. They are the ultimate in fidelity for two-channel sound!
HRx DVD-R data discs contain exact, digit-for-digit copies of the original Reference Recordings 176.4 kHz / 24-bit digital masters. This is the ultimate in fidelity for two-channel sound: TRUE high-resolution audio, ready to load from DVD-R data discs onto your computer music server or playback on a player such as PS Audio’s Perfect Wave Transport.
Why did Reference Recordings decide to make HRx? We have a virtually unbroken history of making the finest possible high resolution recordings. We started with analog tape. We weren’t satisfied with early technology, 16 bit digital recordings, but soon began making HDCD (High Definition Compatible Digital) recordings, in which the process was co-designed by our own recording guru Keith O. Johnson. In the opinion of many, these are probably the best digital recordings ever. Currently we record at 176.4 kHz/ 24 bits, with HDCD, and that is what we put on our HRx discs. Like any quality recording company, we have long been frustrated by the limitations of consumer formats: LP, CD, SACD, DVD-A, etc. No one but our recording and mastering team could hear the full beauty of our recordings! ALL of the consumer formats downgraded the true sound of the master tapes, either because of the limitations of the format itself or of the playback equipment. Computer music playback is the new frontier, and we applaud the brave audiophiles who are its pioneers! The WAV files on HRx are exactly the same as our master recordings. As long as the playback system you use does not convert or corrupt the bits, they will sound as wonderful as our original masters. HRx Notes by Keith O. Johnson
2B. What are the system requirements to play back HRx? Your computer or music server must be able to read DVD-R discs and must read WAV files. Your media player and sound card must be able to output 176.4 kHz, 24 bit audio files. You must have a large amount of hard drive storage space available. One HRx title can take up to 4.7 GB of space. You must have software to manage the music playback. One example is Media Monkey. To realize the fullest potential of these master recordings, we recommend using very high quality equipment with proper, low jitter re-clocking, feeding the best possible external DAC. We recommend consulting a computer music specialist to set up a system to play back HRx.