LPSU powering hdd DIRECTLY - HOW?

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First ever post here.

The question context is re a Music Server, substituting a LPSU is to eliminate noise from SMPS.
Conventional means (which I followed) is to install a Pico-psu of some brand, power it with a lps to run the motherboard with "clean" power (or at least cleaner than ac) and go from there - no problem, that.
My difficulty arises from trying to run the server's drives with an lps, in order to circumvent the smps in the pico psu's that run drives - in essence re-introducing the very noise that a lps is to remove!
The solid state, single voltage (5V) drive was no problem, using a Teddy Pardo 5/3. Different story with dual voltage (12V & 5V) hdd from a single lps, in this case a Teddy Pardo 12/4.
My ignorance led me to assume that the hdd's dual voltage provides a choice of whichever SINGLE voltage is presented to the hdd - wrong!
Twice, I've connected the yellow/black leads of a sata power adapter (cutting off Molex end and the red/black 5V leads, and soldering those to two different types of terminations that accept the 2.5mm female barrel connector coming from the TP 12/4, but the hdd won't power up with only the single 12V wires, it "obviously?" wants to have BOTH voltages present at the sata connector in order to function.
Now, I know I'm not the only person running a LPSU to power drives in a computer, but I certainly am missing something (brains?) that is blocking my path to making the hdd work.

Can anyone help me out here and provide a solution to this problem?

Thank you kindly, I appreciate you confirming my slowly-dawning realization.

Looks like I'd have to split the TP 5V/3A in order to achieve that; given the benign load demands from the ssd and the hdd (not used for boot, only .6a at read/write), do you foresee a problem with using that means?

Best Regards
Just to let you know that I used the two Teddy Pardos exclusively for the hdd; works as it should (and the results are simply FABULOUS, worthy of the effort/expense, considering that the hdd is most critical).
Since I also have an HD-Plex 100 on hand, running the mobo, used its 5V output to run the ssd. Done deal, great to go.
Thanks for your help!

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