has anyone tried PS Audio perfect wave duo

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

Almarg, I think the Memory Player uses flash memory or claims to. I don't remember whether it retains its information, however. What is in this memory can then to downloaded to the hard drive.

Tbg -- From the owner's manual:

The memory for the PWT is not located in the rear SD card as is commonly assumed. The rear panel SD card holds the cover art and song title information as it is acquired. In addition, the SD card is used to program new firmware in the PWT.

The SD card is flash memory, of course, but as this indicates it is not what is used as the buffer memory for the music.

Regards,
-- Al

Any other beta testers besides Mr Darby? Comments?

The buffer in the PW Transport and PWD Bridger is a RAM chip very similar to computer memory.

Also, they haven't decided if the Bridge will be wireless or not yet (I think it might have been another thread someone asked about that). They are considering doing something like Sonos does where you can plug a device into the router and create their own network mesh that doesn't bother depend on the limitations of standard WiFi.

This from the horses mouth last night (Paul of PS Audio).