dac 20bits with SCD1 16bits output as transport?

The question has nothing to do with the DAC. The format of Cds are defined in a publication which is used to make sure that players and media work together. So ALL CDs are sampled at 44.1 kHz and 16 bits. Many CD players have DACs which use a higher rate than the Redbook (most outboard DACs as well), however the CDs are still 44.1/16. These DACS convert that data with signal processing algorithms to a higher rate for conversion to analogue. This 'oversampling' or 'upsampling' (depending on the technique can theoretically improve the conversion (though quality of the analogue stages and implementation of the circuit can be as important to the overall sonic result). The readouts on DACs usually refer to what is coming in (in the case of a CD always 44.1/16) not how the internal processing is happening. SACD does encode on the disks higher sampling rates and bit depth, but there is not yet a transmission standard so ALL SACD player output data like Redbook CDs when used as transports. HDCD's do have a way of coding higher resolution withing the redbook data stream so if your DAC has a decoder, these can sound very good. XRCDs are just high quality recordings and pressings, I think. Data-wise they are not different.

Well said, Fineberg. XRCD's are still 16 bit but use a special high quality mastering process to derive the 16 bit CD data from a higher resolution source.

BTW, the HDCD processor samples at 88.1 khz and 20 bits (if I remember correctly). It applies psychoacoustic priniciples to reduce the data stream to 44.1 khz and 16 bits. The HDCD encoder applies a fixed set of processes to perform the data reduction. It encodes information on the process used at a given moment by modulating the low order bit of the 44.1 khz output stream.

The HDCD decoder in your player/processor decode this information and applies the appropriate inverse process instant-by-instant to the 44.1 khz 16 bit data stream from the HDCD to generate a 44.1 khz 20 bit stream for the DACs.

Also the HDCD decoder incorporates a reconstruction filter that is a perfect complement to the filter applied on the encode side.

Fineberg &Ghostride45, your information was helpfull and well receved,thank you so much, Kike

I am using Sony 777es with Tact RCS 2.0 D/A converter/digital preamp. The Tact unit is capable of accepting higher bit/resolution rates from the source but it can't upsample on its own (as of yet). I just read an article in Bound for Sound by Martin DeWolf who uses an upsampling unit from GW Labs which according to him is just great and it seems that he realy fell in love with it. The good thing about it is, it costs only $399 direct from the manufacturer. I just ordered one and it's in the mail. I hope to report back in couple of weeks.

The high setting is only enabled if you aree feeding a digital signal with higher bit length, 18 or 20bit if I'm not mistaken.
I just bought one myself to replace my wadia x64.4 upgraded to 27, it kills a wadia 861 with just 1 note of piano, it is amazing, don't sell it, it demonstrates that technology doesn't mean music. you basically need to increase the bit depth only it is not the upsampling rubbish we hear about... -:)

Frederick