I have a couple of HDCDs that are 24-bit. How exactly will Foobar handle those ?
Will it treat it like a regular CD (16-bit) ?
Are there any options that I need to specifically set ?

My question is for both - playing the disc directly in the drive OR ripping to a wav file using EAC.

Why don't you try playing the CD?? One test is worth a thousand opinions.

EDIT: Never mind. Was thinking of the wrong thing.

Somebody please correct me if I'm wrong, but AFAIK foobar2000 will ignore the HDCD data and play (and rip) it like a regular 16-bit audio CD.

and thats how I posted in the first place sir..I did play the hdcd and the status bar on the bottom displayed the same information as it displays when playing the CD and the ripped file. Hence the question...what is it exactly doing when it sees an hdcd ??

HDCD are not 24 bit, they are 16 bit, just like any other CD. Please use the search function, your question has been answered about 100 times already.

Thats what it was I was going to say. HDCD's are just 16-bit audio with some special process that somehow can supposedly be turned into 24-bit when playing or some nonesense. CD's can't be anything but 16-bit audio.
http://wikipedia.org/wiki/HDCD
So by ripping the CD sa standard 16-bit audio your not missing anything. You just may not be able to decode whatever the extra information is, if there is even any there. I've never heard of an HDCD compatible hardware or software player.

Well, WMP has long had the feature. Link
And also, the achieved bit depth is 20-bit, not 24.

HDCD does work and there are many hardare players out there that can decode the HDCD info stored in the least significant bit. As far as software WMP can perform some of the functions that a hardware player can and probably WMP will be the only software that will be able to decode HDCD information since Microsoft bought the technology. Your uninformed statements won't help anyone, so better read up on the subject or don't reply at all next time. The gain from HDCD depens on the sound engineer decision for that particular title.

Maybe it's a bit OT but: I have Tool - Lateralus in HDCD. Does the cd player need to be compliant or the amp? The screen on the amp says it's a HDCD when I play it.

At the latest, whatever is performing the D/A conversion needs to be able to "decode" HDCD information. It depends on your setup which component actually does it, could be the CD player (reading 16bit CDDA data, decoding and sending either a 20+bit digital signal to the amp or performing D/A conversion before sending analog signal to the amp) or an external DAC, preamp or amp being fed with the raw digital data from the CD.

If your amp shows that it recognizes the data as HDCD content, chances are that it is the device that's decoding it as well.

But it's still 16bit, not 20 or 24.

(simplified) It's 16bit data with defined compression / limiting settings applied in certain places and control information for that hidden in the least significant bit as dithering.

HDCD decoders look for this control information and revert compression / limiting on the fly. The decoded result is said to be equal to a resolution of 18-20bits.

So by ripping it like any other CD wouldn't the extra HDCD info still be in the audio? Couldn't it also be played back in say WMP and be recognized as HDCD content? Honestly, while 20-bit audio may be nice, is it really any different than 16-bit sound quality wise? I'd like to see someone ABX the difference at least. I thought higher bit depths were important mostly for editing.

Yes, the HDCD info is still in the audio after extracting data from the CD. In theory WMP could still recognize it, and if you play such a file (in any lossless format) through a bit-perfect digital output into a HDCD-enabled DAC, you should indeed be able to get it to perform HDCD decoding.

As for the potential differences in quality, I suggest you to visit the excellent forums at hydrogenaudio.org and do some research there

I am aware there is more audio data. I was only referencing an audible difference. It would seem to me it would be easier to ABX 44.1 KHz & 48 KHz than 16-bit & 24 (or 20 in this case. Although for 99% of folks it would likely be impossible. I recall reading such a debate on these forums a while back actually about whether things like DVD-A actually sound any better than CD audio. But for audiophiles, why the hell not, right? If it makes you sleep better at night then it's good. Same reason I only use lossless formats, may not be able to hear the difference, it's just more satisfying for my unreasonable brain. Plus with lossy, once it's gone it's never coming back. Are HDCD's even still made? I suppose it would be a handy component to have for foobar, but I doubt it will happen since there are no decoding specs, short of someone reverse engineering WMP's component, if that would even work. Regretfully I own the SACD of The Dark Side Of The Moon, and I've never heard the SACD layer and I doubt I ever will for similar reasons.

The main audible difference would be more dynamics. Mahavishnu Orchestra - The Lost Trident Sessions had 3 dB more dynamics after I recorded the output from WMP and compared the waves. It didnt even say it was a HDCD anywhere so it was a very pleasant suprise since I love that album. Speaking of SACD and DVD-Audio the main reason one would buy one isnt really beacuse theres any audible benefit due to the format but due to the fact that they preserve more dynamics during mastering since those formats were made for audiophiles. Normal CDs these days are unfortunately mastered for people with boomboxes.

Since you have the recent DSoTM release with the SACD layer you should read this article:
http://www.stereophile.com/news/11649/

Got it. Having better dynamics is a big plus. That is an interesting article. I've read plenty about the crap dynamics on this DSOTM release. Until SACD's can be copied easily in a pure digital way or even played on a PC I won't hear it. I wonder how long it will take for DVD-A and SACD releases to suffer from the over compression most CD's have. The higher bit-depth allows for more dynamics, although CD's have a pretty decent amount, the people mastering them just don't use it properly.

It's already the case. There's nothing in those formats that enforces proper mastering, anyway, and CD already has enough dynamic range.

It's simply not a technical issue.