theta casablanca 3 audiophile qlty stereo sound?

Depends on your definition of "high end" stereo sound. This is a pricey pre/pro and my experience with pre/pro (in this general range, ie. pretty expensive) is that they can do a very admiral job with 2-channel, but not to the degree that a good to very good 2-channel preamp can do. This being said, I am strongly considering selling my existing (very good) preamp and sticking with the direct pass through analog preamp in my pre/pro (which is a new Krell HTS 7.1 which takes its preamp design from the Krell KCT - the reason I bought it in the first place). I did find after buying it, that it was not quite to the level of a good 2-channel preamp, but have now decided that it is, hopefully, good enough for me.

Theta offers three different levels of DAC's. Check out their web site for details. I've used the CB3 with their top of the line DAC's for years. This is one of the few Prepro's that can pull off sounding excellent in two channel. Just make sure you go with the higher end DAC's. Might also want to looking into a prepro with a Theater pass thru allowing for a seperate higher end 2ch Dac/preamp for your music. Just a thought.

isnt DAC is for CDP? Does theta built in DAC card only benefit to CD?

Theta builds higher end DACs right into the CB3. Goto Theta's web site for all of the details. Or search here and AVS forum for details.

The benefit of the built-in DACs on the Theta is a matter of opinion in terms of the benefits delivered. Obviously, the better the quality of your CDP, the less benefit the built-in DACs will deliver. However, if one has a mid level CDP or already just has a transport, then the built-in DACs can be a real benefit. This is all based on 2-channel listening. Having them can increase flexibility, no doubt (adding digital sources with either no internal DAC or a poorer internal DAC) or possibly doing away with CDP's in favor of straight transports (nice if one already has a 2-piece transport/DAC and they find that the DACs in the Theta are as good as their existing stand alone DAC???).

Pre/pro don't have HT passthrough in the sense that a 2-channel preamp does. What I believe stick is refering to is either a full analog bypass that allows the 2-channel signal to pass through the pre/pro without any processing (outside of gain in the analog domain) for the cleanest/least compromised affect on the signal.

Typically, HT passthrough refers to a feature on a 2-channel preamp that allows the prepro to deliver its front left and right output signal (that would typically go to the associated amps) for a movie (for example) to pass through the 2-channel preamp without requiring the user to adjust the volume from the preamp, but performing all volume control via that of the pre/pro. This allows one to connect their higher quality 2-channel analog signals directly to the 2-channel preamp, leaving the pre/pro completely out of the 2-channel chain for optimal performance. In essense, this allows one to maximize performance for 2-channel and also for surround sound all in the same system!