I'm not sure that the A1000 support Atraclossless but the A808 does so if this is true then the A1000 is transfering and converting to lossy and the A808 is transfer the loss less file which would account for the size difference and I'm assuming that both players are reporting the same conversion rate. First, when transfering files is Sonicstage converting the files first and the transfering, If not the an previous converted file is being transfered. Quick check in sonicstage select the option to not delete optimized files. Import a file to one of the players. Find where sonicstage maintians optimized files (most likely under Document/Settings -> All Users -> Sonicstage -> Packages -> Optimized. Not to file size, now in Sonicstage select the option to delete optimized files this will remove this file so that when it is transfered again a new optimized file will be created. Not transfer the same file to the other player and check the optimized directory again. Are the files the same size? If not one file is being converted to AAL and the other to lossy.