Are my CAT5 and router my weak link?

If I understand it correctly Ethernet cable connects computer to wireless router. If that's the case then it is in some distance from the DAC that has built in wireless receiver eliminating capacitive coupling and leaving electromagnetic radiation to consider. This radiation is practically eliminated, not only by very tight (>2twists/cm) twist on CAT6 cable, but also the fact that signal is balanced. Radiation is limited to common mode noise coming from the system (perhaps power supplies). This noise (whatever the source is) has to be strong and at least 30MHz to make effective (1/10 wave) receiving antenna of typical 1m interconnect. At this frequency skin effect is very strong and interconnect's shield is working very well (Noise from crude computer switchers is in the frequency approx. 100kHz and has no chance to be received by 1m antenna). Of course it would be wise to keep this Ethernet CAT6 cable as short as possible and far from the DAC.

Think of it like this. Your data is transfered from a NAS into a buffer in the PWD Bridge. If you copy an excel file from a NAS to another node on the network, it will be bit for bit perfect (i.e. the exact same bits) all the time, irrespective of quality of your cable. The same applies to your music file. It gets tricky when timing information is involved - not the case here. The bridge is completely asynchronous.

Kijanki - Your expertise in this area far exceeds my own. There may be good technical reasons to doubt that an ethernet cable can affect sound quality. Nevertheless, the effect I heard when I replaced an unshielded Cat 5 with a shielded Cat 6 was, from my point of view, too obvious to be attributed to placebo.

When a listener reports an experience that challenges an accepted explanation, it raises the question of the reliability of the listener. But it also raises the question of the reliability of the explanation.

Bryon

Using wireless LAN connection (Wifi) provides the best solution for physically isolating sensitive audio playback gear from potentially noisy computer gear as an insurance policy for best results. I would recommend everyone use this approach to connect their computer gear to their stereos and rest easy at night.

Bryon, Your case might be different. Perhaps Ethernet cable was in close proximity to analog wiring (interconnect or speaker) or I'm just plain wrong about it (I was wrong once in 1960). Audio is not exact science and I'm just trying to understand. Maybe balanced drivers are never exactly symmetrical and there is some high frequency component. It is possible that computer you used produced high frequency common mode noise. I hope Al will help with this.

Mapman, I Agree 100%. Not only that computers are noisy but also can and should serve its main function and therefore its location might be remote (mine is across the room). I use my computer during music playback because I know that it cannot change timing on the DAC side. For the same reason I use free Itunes, cheap computer, not a lot of memory, standard external hard disk etc. SIMPLICITY.