Daisy chaining CX220s

I have used Slink-e with a Sony CX220 successfully. I would like to add another 220 and it is not obvious to me how to connect the audio portion of the two units. Following are the options that I think are available. I would appreciate any comments or suggestions:

1 Buy a CX240 that has L/R audio (stereo) in/out and "daisy chain" the two units. Anticipated disadvantages are the 240 is more expensive (for features that I don't need such as a keyboard input) and I couldn’t take advantage of the digital audio output (optical). The advantage is that I think the two units will be nicely integrated under Slink-e control, perhaps with pre-queuing when alternating units in a playlist and with overlapping fades capability.

2 Buy a second CX220 (my preference) and run audio outputs from each unit independently to my preamp/processor where I could switch from one to the other. Disadvantage is that Slink-e would not be in total control since I would have switch the processor as the playlist selects from one 220 or the other. This approach would also eliminate the possibility of overlapping fades.

Any suggestions? Should I modify a 220 so that I can "daisy chain" the two? Is there an in/out modification suggestion for the digital stream (like an optical "Y")? If not a digital mod then any suggestions on how to add in/out L/R (stereo)? I don't mind cutting metal and soldering components.