I can not put my arm in the fire for the recordings in question. I have TONS of genuine DSD recordings and know exactly how DSD128 differs from DSD64, let alone PCM, even 192/24. Redb....what?
My last post till you get The Big One - concentrate on Binaural recording(s). Binaural can not be mixed remixed remastered and manipulated as easily as anything else. In fact, binaural is the ideal vehicle to finaly throne the best digital out there, and at the moment this is DSD 128. You simply can not take the full advantages of DSD in multimiked/multichannel recording. Binaural is by default 2 channel and is the closest approximation of the live sound you can possibly achieve.
The ULTIMATE proof of the above statement? Instead of dummy head of whatever description, use your own head and headworn mics. You will hear exactly as unimpeded by the equipment - and the moment upon returning home you WILL be eager to hear the recording you just made. The best reasonably priced commercially available DSD recorder would be Busman modified http://www.busmanaudio.com/mods.html Korg unit - up to you if you opt for portable or rack machine. The best tool for the listening would be AKG K 1000, followed by Stax Lambda Pro equalized by ED-1 Monitor Diffuse Field Equalizer, which was made specifically for Lambda Pro.
Strictly speaking, Lambda Pro DOES satisfy your requirement for 20Hz-20kHz response. At least TWICE.
If you even then do not hear the difference between redbook and DSD128 played natively, you are either deaf, biased beyond description, heavily in the pocket of Redbook, or - dead. No other option.