Actually I have the clock already ! For Sacd I have a limited collection ( around 100) compared to CDs. I believe Esoteric products have wordclock inputs as well.
How would you compare Scarlatti transport vs Vivaldi ? and even if not 100% comparable Scarlatti transport vs Vivaldi upsampler network input ?
I did my Vivaldi stack in 3 steps - 1) DAC + Upsampler 2) Clock 3) Transport. For steps 1 & 2, I used my Esoteric K01 as a transport. dCS sources the Transport drive mechanism from Esoteric. The Esoteric does work fine with the Vivaldi clock (you only need 44.1 group 1). Jfrench is correct you can't play SACDs through the Vivaldi DAC from the Esoteric, only CDs via single AES or SPDIF connection. For SACDs, you run analog out from the Esoteric straight to your preamp. If you have a PS3, Oppo 10x or the right BluRay player, you can also rip your SACDs so they can be played via the network or USB input on the Upsampler to the Vivaldi DAC. I lived very happily with the Esoteric as my transport and only bought the Vivaldi because I was offered a good deal on it. There is an improvement with the Vivaldi Transport but it is subtle and I could only really tell when I listened to the two transports back to back. If I had heard them on different days, I'm not sure I would have noticed the difference.
If you do consider the Esoteric as a transport, I'm not sure there is any real advantage to the K01x over the K01. The improvements in the "x" were mostly in the DAC and the USB input to allow it to work with higher PCM sample rates. Since you already have the Vivaldi DAC and Upsampler, you don't need the "x" and used K01's can be had for $8K or less.