has anyone tried PS Audio perfect wave duo

Shazam -- Yes, it makes (bit-)perfect sense! Thanks very much.

So the benefit (or at least a benefit) of the large cache is that it allows time for the large number of retries which may be attempted, at least with marginal disks, which in turn would essentially eliminate the need for error interpolation.

One question that brings to mind that I would want to assess is how well-controlled the acoustic noise produced by the drive mechanism is, considering that it is running at considerably faster than 1x rates, and it will occasionally shuffle around and backtrack for the re-reads. I'd assume that is addressed well in the design, but it seems like a relevant question to raise.

Another point relating to their descriptive literature, though, would be that claims that no error correction is used are probably mis-stated. EAC's site, in fact, states that with the EAC software "if there are any errors that can’t be corrected, it will tell you on which time position the (possible) distortion occurred, so you could easily control it with e.g. the media player." In other words, I would envision that the PerfectWave Transport does away with the combined error correction/error interpolation provisions that are provided by more conventional cdp drive units, but then makes use of the Reed-Solomon error correcting codes in its own processing, to correct all errors which can be bit-perfectly corrected. There would seem to be no reason not to do that. The difference relative to a conventional cdp is, if I am correct, that no error interpolation (i.e., estimating of what the sample value should be) is performed -- that is what is eliminated by the multiple re-reads.

FYI, re your statement about the PW using EAC, one of the pages at their site indicates that their MREC (Multiple Read Error Correction) process is "similar in concept to EAC."

The benefit of all of that, of course, will vary with the physical quality of the cd, and perhaps the age and condition of the laser. But there is no question in my mind that the I2S interface approach is vastly preferable to the conventional interfaces that multiplex and then de-multiplex clocks and data, and that is perhaps the most significant advance provided in this design.

Thanks again for the good explanations.

Regards,
-- Al

i find it surprising that ps audio did not use one of three 32 bit dacs. perhaps one of the dacs which incorporates such a chip will give ps audio's productm competition, e.g., the buffalo dac.

There are well known and praised digital front end systems on the market listed at $68,500, $29,000, and…I don’t know off the top of my head what MBL’s best are listed at. Now, we have the Perfect Wave system listed at $6,000. Comparatively speaking, this cannot be considered “over-priced.” I just bought the PWD for $2,000 (plus trade in). I have written about what this system sounds like. It does not deserve comparison to the DACs that I am familiar with in the $5,000 and under sector. The PWT/PWT should be compared to the super high-end digital front end systems on the market. It may, or may not hold its own with such products, but I can verify that it is superior to most of the well mentioned systems. Personally, I have opted for the forthcoming Bridge instead of the PWT (transport). To me, a high-end music server makes more sense – why bother with individual CDs…

2chnlben, if I understand this right, the Perfect Wave merely reads the cd into flash memory and then replays it. Why this is then not added to a hard drive seems unfortunate to me, but I can see why a perfect copy would be better than relying on the cd player to get the data just in time to send it on.

I have not heard a demonstration of hard drive to flash drive for replay versus straight from hard drive. Perhaps this does make a difference.

I suspect that it is not flash memory which is being used, but rather dynamic RAM (random access memory), similar to computer RAM memory except with much less capacity. Hard drives and flash memory retain what has been stored when power is turned off, while dynamic RAM does not. However, RAM is much faster, and also cheaper and more compact. Also, flash memory has a limited number of write cycles it can handle before failing, the number being fairly large but potentially a significant factor in cdp or transport lifespan. And it requires sophisticated memory management algorithms to minimize that limitation.

In principle a transport could certainly be designed to utilize either a hard drive or a flash memory, but it would add to the cost and complexity, without providing added value for many or most users.

Regards,
-- Al