Guidocorona: No external clocks; too much money, not enough space in my system. Avguru: well, I listen based on what I hear live, and because I go to so many concerts, I have never found any two channel system to sound anything like what I hear in the hall. However, the modern multichannel systems don't work for me either--too software-dependent, too many mikes, and when you are supposed to use 5 identical speakers, how good are any of them going to be? For years I've used a SONY 505 ES delay/ambiance unit from the mid-'80s, which only requires a small rear channel amp and two small speakers similar to the front speakers in overall character, and what I hear through that set-up is similar in kind to a real hall, although of course not in degree. In four channels, the X-01 throws a wide, close (to my seat) soundfront, and sounds extraordinarily like my 8th row center subscription seats. The Omega presented a more blended, slightly narrower soundfront, much more like my 25th row center seats for my other subscription. The turntable is somewhere in between. General preference? Well, I did buy the X-01 and sell the Omega, yes? If I turn off the rear speakers, I hear all the things reviewers and audiophiles obsess over--layering, imaging, etc., but they generally sound somewhat artificial, because there is no sense of the hall. Sorry, I'm sure that didn't help you. Last thing you asked: I find DVD-A, sonically, noticeably better on the DV-50 than SACD: greater dynamic range, clearer midrange, definitely cleaner in the low frequencies. Better playback or better medium? Don't know. Probably doesn't matter--as a purely audio medium to me DVD-A seems too clumsy to hang on except as a marginal foremat, and where's the software?