Timely thread. Did a similar experiment with my 352 this weekend. History. Purchased the 352, C39 and MCD205 after discovering McIntosh sound with a 2105. Used unbalanced IC's between CD player and C39 and balanced between C39 and 352. Cables. Unbalanced cables were much older high end Monsters (I know) and balanced are homemade Neutrik connectors soldered to high end recording studio line level cabling. Ever since hooking this system up several months ago I was disappointed with the sound quality. I kinda felt like the original poster about his 402. Collapsed soundstage, no depth, unruly bass etc... Anyways, finally went out and got some mid level Audioquest unbalanced cables for CD to C39 since reading threads about IC's changing the system. Wow. There was the culprit. Tone, soundstage, depth, refined bass response etc... was there. I felt like the components were finally able to communicate with each other and display their true colors.
I decided to try a change in my cabling between C39 and 352 given my results above. Decided to try unbalanced between pre and amp with Audioquest and found my DIY balanced cables were actually quite good. I didn't experience the amazing difference compared to replacing those terrible Monsters. The differences I experienced was the unbalanced connection had very similar tone, soundstage etc.. but I felt like the music was shouting at me and was harder to pick out smaller details (more lively like described above). The balanced seemed to have more depth and clarity without harshness. Both ways sounded good but I just preferred the balanced presentation.
All of my cables are copper.
I decided to try a change in my cabling between C39 and 352 given my results above. Decided to try unbalanced between pre and amp with Audioquest and found my DIY balanced cables were actually quite good. I didn't experience the amazing difference compared to replacing those terrible Monsters. The differences I experienced was the unbalanced connection had very similar tone, soundstage etc.. but I felt like the music was shouting at me and was harder to pick out smaller details (more lively like described above). The balanced seemed to have more depth and clarity without harshness. Both ways sounded good but I just preferred the balanced presentation.
All of my cables are copper.

I found out where the problem was! It was the damned filter that was killing the sound. :thumbsdn:I connected my 402 straight to the wall long ago but somehow I never tried to connect the pre straight into the wall. I always thought that filter improves both the source and the preamp. Was I wrong! When I plugged it straight bypassing the filter the music came alive, became easy on the ears and started to flow. The soundstage improved dramatically. Now the balanced connections sounds awesome without all the harshness and digital-ness that I was there before. I was so dissapointred with my upgrade before that I actualy put both C46 and 402 for sale feeling that they don't give me any substantial improvement over 6900. I retract my former pissed-off comments and proudly say that my faith in McIntosh engineering is fully restored.