Are my CAT5 and router my weak link?

Any cable that is conducting high speed digital signals, such as the OP's CAT6 ethernet cable, firewire cables, USB cables, etc., and that is located in physical proximity to the audio system (e.g., in the same room), can radiate or couple RFI (radio frequency interference) into the audio system, with effects that although unpredictable could conceivably be both sonically significant and cable-dependent.

Cables that are conducting signals that are involved in the timing of D/A conversion, such as (apparently) the clock cables Jfrech is referring to, can of course be expected to be much more critical, as a result of noise pickup, ground loop, and impedance matching issues that can affect jitter.

If the CAT6 ethernet cable the OP referred to is in the same room as the audio system, he may wish to consider experimenting with inexpensive shielded ethernet cables, as member Bryoncunningham described doing in this thread. See the posts in that thread dated on and around 2-16-12. Inexpensive ethernet cables are commonly unshielded, but good quality shielded cables are also readily available at low prices.

Regards,
-- Al

I work with this every day. Shielded cat 5/6 cables test with LOWER bandwith than the unshielded types. I have installed and tested thousands of miles of this cable and the only time I have used shielded in in severely compramized locations like radio stations with broadcast antennas on site. The shield compramises the magnetic field genenrated by the twist of cat 5/6 by phycally restricting it within the shield. Each pair of wired(4Prs.) is twisted at different ratios per inch to generate specific magnetic fields to control cross talk and give excellent speed. The shield is always a compramise in the data world. I have even had to replace shielded with unshielded. The whole idea of the twist is to negate the need for a shield.

I can confirm what Al has reported about my experiences when I replaced an unshielded Cat 5 cable with a shielded Cat 6 cable. The result was more resolution. A lot more.

The $7 shielded Cat 6 cable resulted in a bigger improvement in SQ than several $1,000 power cords and several $2,000 interconnects. Yes, I know that sounds crazy. I can't explain it.

I'm not saying that other systems will benefit similarly. In fact, I doubt it. But it's certainly an affordable experiment.

As far as the router goes, I too have a router indirectly connected to my audio system (outside line -> 15' shielded Cat 6 -> router -> 1' shielded Cat 6 -> ethernet switch #1 -> 20' shielded Cat 6 -> ethernet switch #2 -> Sonos -> audio system). Ethernet switch #2 is a bus between the computer and the Sonos. Ethernet switch #1 has only one function: to sever the connection between the router and the audio system...

The router is left on all the time. I have the PSU for ethernet switch #1 plugged into a rocker switch, which is itself plugged into the wall. When I listen to music, I flip the rocker switch to kill the power to ethernet switch #1, which kills the connection between the router and the audio system. Don't know if any of that is relevant to your setup, but it's another easy and affordable thing to try.

Bryon

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.