Thanks for the link to that great article!
I expect to receive the two items pictured in my post on the previous page either today or tomorrow, but (bummer) I'm no longer in possession of an Objective DAC that I can test, so here's a proposal...
I can tell, just from reading your recent posts, that in addition to having two ODACs that you can test with my proposed "solution," it seems you certainly have the skills and equipment with which to do a much better job than I could, assessing whether or not the idea is viable.
If you are willing, and for the good of the ODAC user community, I'd like to pass the baton to you and just give you (for keeps) the USB injector and 5V power supply. Seriously.
I was going to try testing them with the CEntrance DACport LX I've bought, just to see if it works at all, but you seem to be far better equipped to measure voltages, check polarities, etc. -AND- to see how the ODAC performs with it.
I think members following this thread would be much better served if you evaluated it, than me, even though your ODACs aren't exhibiting any problems, currently.
Later, if you find that this injector + power supply combo does a good job of providing power to the ODAC (providing correct voltage and polarity, for example), and you find that it introduces no issues with sound quality, you could, at your choosing, pass it on to someone who's actually suffering power-supply symptoms with their ODAC. If, on the other hand, it doesn't work well with the ODAC, for any reason, feel free to keep it for other projects - there's no need to return them to me.
Send me a PM with your mailing address, if you're interested. I really think you're the right guy for the job.