I had considered the Cary CDPs as a one box solution prior to going the seprates route. I'm using an Alesis ML9600 as my transpot (also can be used as a HD player and CDR) with my Audio Mirror DAC (D1 not the new D2). I had both modified by TRL (see my review of the Audio Mirror). The primary reason I went with separates is that I favored the non-os sound that products like Audio Mirror, Audio Sector, Audio Note and 47 Labs offer. The sound is smoother and much more analog like. If you want to read more about this philosophy go to the Audio Note and Shigaraki websites to read the designer white papers.
I think the Cary CDP is a great unit. I have owned several Cary products including a Cary V12i (similar to your Six Packs) and an SLP-98. I used my digital set-up with both these Cary products and the sound was excellent. I tried the Benchmark with the Alesis and Cary set-up and did not like it. One option to consider is to use the Cary as a transport with a non-os DAC and then if you like you can switch back and forth between non-os and upsampling depending on the music. This is an option I seriously considered with a Cary 308T (I wanted tubes as well in the mix at the time). I still may go back to the idea.
I think the Cary CDP is a great unit. I have owned several Cary products including a Cary V12i (similar to your Six Packs) and an SLP-98. I used my digital set-up with both these Cary products and the sound was excellent. I tried the Benchmark with the Alesis and Cary set-up and did not like it. One option to consider is to use the Cary as a transport with a non-os DAC and then if you like you can switch back and forth between non-os and upsampling depending on the music. This is an option I seriously considered with a Cary 308T (I wanted tubes as well in the mix at the time). I still may go back to the idea.