I think Denis is right, I just checked www.synthplanet.com and the SD1 is listed there for US$1732.74 while the X1 is for US$1906.02
BUT, in order to match apple to apple, SD1 should be compared to the X1 with Hard drive (because the SD1 comes already with a built in Hard drive, it’s not an option).
The price for the X1 with HD is even more expensive US$2223.05
Does the absence of speakers in the SD1 have to do anything with the lower price?

Maged