HDCD Question....

I believe that any CD/DVD player is compatible with HDCD discs in that they will play them with 16 bit resolution, but you need an appropriate HDCD chip set to get the 20 bit equivalent resolution and other benefits HDCD's are capable of. Considering the fact that there are over 6000 titles with HDCD decoding which probably outnumbers all other "high resolution" digital formats combined, your question is an excellent one. I don't believe any Sony players have the HDCD chip set. There will be an HDCD logo on the player if it is capable of fully appreciating the benefits of HDCD. The biggest differences between HDCD and SACD is that there are many more HDCD titles currently available are usually less expensive and that HDCD can be played on any CD/DVD machine, while SACD's should be capable of considerably better sound than HDCD's, they require specific machines to play single layer discs, dual layer discs should be compatible with all machines and the number of titles is of course limited and complicated by the fact that there are in fact two variteies, one of which as previously described requires specific machines to decode and while growing there are less titles and those titles can be more expensive that standard CD's or HDCD's.

The easy answer to your first question is "No". HDCD is a proprietary encoding process (license owned by Pacific Microsonics) and HDCDs, while playable on regular CD players, sound better on HDCD-enabled CD players - HDCD-encoding is not decodable by conventional CD players. The more complicated answer may be "Yes and No." There exist, apparently, HDCD-decoding amplifiers, but I do not know how they work (I have been under the impression that HDCD is essentially a DAC filtering algorithm). If they do exist, theoretically one would not need both an HDCD-decoding CD player and an HDCD amplifier/receiver.

Sony SACD players do not, to my knowledge (I own one), have HDCD-decoding capability.

HDCD discs should be compatible with all players. If a player is equipped with an HDCD digital filter all the better. HDCD is a process whereby recordings are laid down in 20bit vs 16. It's still PCM.
SACD uses DSD (Direct Stream Digital)to capture the waveform in an unfiltered 1-bit 64x over-sampled form.

So 2 different animals. PCM with a lot of filtering vs SACD with virtually none.

HDCD discs sound wonderful, in my opinion. I use an Arcam FMJ-CD23, which is HDCD ready. A red indicator light comes on when a HDCD disc is loaded into player. I'm surprised how many CD's are encoded with the HDCD process without any codes or notification on the jewel box info or on the disc itself. Arcam's lower priced model has HDCD playback also. I wish there would be more publicity and consumer awareness about the HDCD process. SACD may not be the format to go to if HDCD is so good. Check out any Reference Recording's HDCD discs. They are great. Keb Mo, k.d Lang and Patricia Barber discs are sometimes HDCD availible also.

Almost all of your questions seem to have been answered except, maybe, which SACD machines are HDCD-equipped when in their CD playback mode. The Sony's are not but the Classe Omega is, and I understand that the Lindemann D-680 is also.