Redbook Audio Aero Prima vs SACD palyer?

It depends on which SACD player you're talking about. Of course, if you're going to drop a couple of grand on an SACD player, it'll probably be a good one. The Prima has a pretty good reputation around here for redbook performance, but it can't do SACD. Just make sure you're SACD player can do redbook CD as well as the Prima.
But then, do you really plan on dropping a lot of coin on SACDs? They are expensive and the selection isn't nearly as large as it is for CDs.

Golden_ears- I agree with everything you said besides the SACD's being expensive, I haven't purchased a SACD for over $16.99, sure some of the reference Mo-fi and analogue productions stuff retails for $25(which still is not bad for how good they do sound, I have a few of each) but you can usually always find them used for around $15ea. The ones that I am unable to find I am near my breaking point and am going to spend what it takes to get them. All of that being said retail price on CD's has just come down which is the only reason there is a discernable difference between the two format's as far as price is concerned. If you just impulse buy SACD's I bet it could be expensive, but so can regular CD's retailing for $18.99 in some stores still!

You're idea is not far-fetched. I find that my redbook performance equals my SACD performance in most cases.
You will need a DAC to get the best of both worlds if you want true premium SACD and redbook. I use an XA-777ES for SACD, and the TRUTH is that I could live without the SACD if I were playing 24 bit remastered redbook CDs via my ECD-1 DAC. There are a few exceptions, but they are very (too)few at this point.

I am sticking with my Audio Aero (Mark II) as I have a huge investment in redbook and i really don't want to clutter my sources at the great expence of my pocketbook.

I own a Mk2 Model Prima and a Xindak SCD-2 which is an SACD Player.
I have kept the Prima because it is superior to the Xindak on Redbook and sometimes so close to SACD comparing SACD Layer to Redbook layer in a hybrid CD that you have to wonder.
Thankfully I payed the paltry sum of $700 for the Xindak and for that money it is great and now I have the flexibility to purchase either Redbook or SACD.
Probably the one place where SACD shows it's mettle is with Classical recordings. Here there is beautiful naturalness that Redbook just can't match.

What an intersesting "thread". I have a new (I month old) Xindak SCD-2 player, and the rest of my equipment is Kora all tube equipment. I use the SCD-2 to play CDs, as a transport with the Kora Hermes II as the DAC, then through the Kora Eclipse preamp and Galaxy reference amp. The sound is incredible, ........... in fact better than playing SACDs with the Xindak balanced output through the Kora Eclipse preamp and Galaxy amp!!
Would you be able to advise me of any mods I can do, to really get the benefit of SACD, or know of someone who can?

If you like what you have, go buy some more CDs and forget the Mod.

I've had the same experience CD vs SACD. My Wadia 861 sounded much better playing redbook CDs compared to a Sony SCD-777ES playing SACDs. Same music/album, of course. This was in my friend's system using his cables (TARA, V-D), his pre (Spectral) & his power amp (Plinius SA-250).
My experience was brief (few hrs one evening). Many people write that one has to live w/ SACDs for a long time to perceive just how good they are over CDs.
That's bollocks! In my experience, if something is much better sounding, I can tell immediately. It takes me about 1 track on a known CD (music known to me) to figure out whether the sound is better or worse (to whatever I'm comparing it to - electronics to electronics or CD to CD). If one has to live w/ SACDs for a while before perceiving their superiority over CDs then I don't consider that any sort of superiority! It's a slight difference/improvement that I cannot justify as a major expense in my system.
Over on a EMM Labs thread, I read a whole bunch of owners just brown-nosing each other informing all those who read that thread just how good the EMM Labs modified Philips transport is for SACD!! Looks like people justifying their huge investment into SACD (if they didn't justify their postion, they'd look foolish spending this much money!). Most of world has seen marginal (consumer ROI) improvement in SACD. Many people in the audio biz have also written about SACD's marginal improvement over CDs.
Some articles:
http://sound.westhost.com/cd-sacd-dvda.htm
http://www.iar-80.com/page17.html
My intention is *not* to touch off a battle over this subject (it's been flogged already in another thread on Audiogon) but to suggest that the investment in SACD is probably not worth your hard-earned money. Atleast not right now.
If you insist on getting a SACD player, get something inexpensive so that it doesn't pinch you should it not pan out for you for one reason or the other.
FWIW. YMMV. IMHO.

I've had the Wadia 861, the DCS stack(w/o dsd) Sony SCD777ES, Marantz SA-1, PassD-1 with a CECTL1-X transport and I have to say that anyone who doesn't hear the difference between a high-end sacd player and high end cd is just missing something. I just bought a Krell SACD Standard and I'm here to tell you that for 2800 used the cd is equal to the stock Wadia (although you need a pre-amp) and the SACD is equal to the Marantz SA-1. Even the DCS Delius and Purcell with a CEC transport on cd can't touch SACD. I don't mean pcm -sacd conversions(which still sound great), but true dsd recordings can't be beat by anything except vinyl. Really expensive vinyl. Why the hatred for sacd? It's our only hope for a large hi-fi play list. My suggestion would be to buy a sony scd777ES $1300 used(great transport); run the digital out to your dac of choice (1000-2000) and run the sony sacd into your pre-amp. Get both for not much$

I think you have to ask yourself, "how much music am I willing to lay down my hard earned money to buy that is in SACD?" If the number of discs you are acutally willing to pay money for is significant, in proportion to your whole collection, you should seriously consider a good SACD player with excellent redbook (or a very good SACD player and an outboard DAC).

I now own about 85 Hi-Rez discs (80 SACD+4 DVD-A+1 XRCD). All of the music I purchased in these formats is essential to me; it is amongst my favorite music that I spend most of my time listening to. I have about 400 redbook CD's as well. So, before too long Hi-Rez discs will make-up about 20% of my collection. A significant proportion.

Most SACD discs, to me, in my syestem, sound vastly superior to their redbook counterparts. That said, there are some that do not sound that much better than their remastered (20/24 bit)counterparts. But this has been the exception, not the rule. I buy almost all my Hi-Rez discs used or on sale, and will shop around for a good price.

Since I acquired the Exemplar Audio modified Denon 2900, I do not hesitate to buy a remastered redbook disc over a SACD that is priced significantly higher that I don't want to wait to find on sale or used. I recently did this with two Miles Davis CD's when the Borders Store near me had their Jazz Music Sale in August.

That's my 2 cents, good luck,

it probably depends on SACD player my SONY 9000ES (new in 2002 was $1500) really sounds worse them my Arcam ALPHA 6 (new in 1996 was $900) CD player. It was not that big difference on MF A300 (on sale on Audiogone), but since I have Supratek/Clayton combo + Thiel3.6 difference is huge. SACD is just lifeless, non-involving to me, sounds like hifi not like music (I was comparing it on hybrid discs).
So I will be upgrading source next year, I do not have courage to buy expensive SACE player I will take easy and safe route and will by good quality CD source. (Thinking about Audio Areo)