You don’t need to connect the SSD to the LP4 at all; I believe they made this connector just for (in)convenience.
-If you need to use the LP4, I recommend purchasing this 4-way cable and cutting the male-female part off, so you have a straight female-female cable.
-But I really think the best option would be to get this SATA cable and cutting off the LP4 connector, then feeding 5V into the red wire and cutting the yellow wire and the black wire next to the yellow one off.
I’m a little surprised that the SSD uses that much power. The WD Red only uses 0.2W (idle) and 1.4W (read/write).
-But of course, the sustained SSD throughput is likely higher than 144 MB/sec.
I see the following benefits from having the Linux on eMMC:
* If the SSD breaks, you don’t have to re-install (although it’s great to have a backup anyway!)
* Your device will start even if the SSD is broken.
… and the following disadvantages:
* Might be a little more cumbersome to write the Linux to eMMC than a SATA device, because you’d have to do it ON the EspressoBIN, while you could actually connect the SSD directly to a PC and write the SD-card image onto the SSD, then expand the file system.
Good luck on it; I look forward to hearing that you succeeded. 😉