sound sacd discs like dsd Cds?

I was wondering how a DSD recorded rebook cd sounds compared to a sacd played on a sacd player.
I was able to do this exact comparison using Alison Krauss "Live" a DSD recording. I have both the RBCDs and SACDs (the RBCDs came out much earlier and there was no assurance an SACD release was coming, so...).

Doing this comparison made it ever so clear to me that it is the quality of the recording itself, not the means by which it is encoded onto media, which has the greatest effect on what you hear from your speakers.

This is such an outstanding recording the RBCD is virtually indistuinshable from the SACD played back on a Denon 2900 universal player. If I play back the RBCDs on my Wadia 861es then I actually prefer them to the SACDs being played back on the Denon 2900.

I have about 40-50 SACDs but I am thoroughly unconvinced of the sonic superiority over RBCD. Sure I can rationalize 10dB more dynamic range in the mid freqs but in practice I just don't hear it. Maybe if I get one of the new Wadia 781 CD/SACD players?
I have that Akrause SACD too. By any chance have you compared the Redbook Layer of the SACD on your Wadia to the stand alone Redbook? Would to theoretically expect identical sounds or, are these mastered differently I wonder.
Listening to that particular SACD on my SACD player (a modified Sony SCD 777ES, with an Audio Logic output stage), on both the redbook CD and SACD layers, the redbook is pretty close, but falls a little short in terms of decay of instruments and smoothness of voices. A little more etched. Same result, though even less pronounced, when the redbook layer is played back through my Forsell/Audio Logic combination. And keep in mind that the Audio Logic converts pcm to DSD internally, too.
The maximum signal level recorded on a SACD or a DVDA will be the same as the maximum on a CD. In other words, bit 24 of a DVDA represents the same player output voltage as bit 16 on a CD. So what you gain with "high res" is less quantization error for the quiet passages, where only the less significant bits are being used. So if you have music that is mostly loud, probably compressed, the 16 bit CD and the 24 bit DVDA will sound pretty much the same, neglecting improved high frequency response due to 96 KHz sampling. (I use the PCM encoded DVDA as my example because the comparison to PCM encoded CD is straightforward).
Although I didn't do the explicit comparison I would guess that the mastering on the CD layer of the SACD is exactly the same as the mastering on the RBCDs.