Michael at Elijah Audio responded me that he cannot make a solid adapter but requires minimum 5-6cm Mundorf silver/gold wires with silk sleeving between the USB A male and USB B male due to plug configurations. I have asked him how much that would be (without battery cable attached, ie as a hq adapter cable) and are waiting for a reply. I guess using Mundorf silver wires for + and gold wires on - would be a good idea on your interesting project as well? Several others like for example Entreq uses silver/gold wires for a neutral sound.
The solid USB A male to USB A female with blocked 5v pin was USD95 including freight to Sweden BTW. I will order this since it will be a useful adapter (for any USB cable) with the Regen.
I have a KingRex uPower (battery power) that I will use for my Regen when it arrives in November and have no plans to use the original SMPS. Originally thought I could use both the 7,5v and 5v output at the same time...but this was not as simple as I thought as it could potensially damage any connected device in my USB chain..so I will use it for the Regen only. However, I have asked KingRex about it...but still nothing but silence from them. The 5v USB output on the uPower is linear and not switched so it would be nice to use if possible.
You have a very interesting project indeed...but way to advanced for me personally to execute. I wish you all the luck! Do report back IF and when it is all done. Would be interesting to see how it turns out!