Improved SQ, with a better Processor?

Brilliant answer, thanks Mike! 

Davina

There's a theory that the WIFI receiver produces noise.

I use a SBT, wired. Because I don't use Wifi I've disabled the WiFi.

The disabled Wifi is one of a number tweaks, known to improve sound quality of the SBT. Don't know the effect of only disabling the wifi would have, but implementing all the tweaks produced an obvious improvement.

More than a theory. It's a radio transmitter and receiver. It produces noise by definition.

Well, I think you've all convinced me, that I'll have to hard wire the iMac, over WiFi.  

I've got the cable, but it's a bit tricky running the cable from the upstairs to the front room, where the 'switch' and ND5 are. The easiest way would be to go down the outside of the house in a conduit, but I'm not sure what effects the cold temperatures, and dampness would be on the audioquest Ethernet cable. I Don't really want to 'muller' a £150 cable! Has anyone run Ethernets outside?

D

For external application, steel wire armoured cat5 will do the job.

No need for conduit or a £150 cable and it will be a lot easier to install.

I've had 30m of Cat5e (nothing special bog standard off the reel stuff) running externally between my study and lounge for over 7 years now supplying the Hi-Fi. Apart from the insulation going a bit hard due to UV exposure it's still fine.Just ensure it's clipped firmly to the wall and it'll last. .  

If you still have any concerns about optimising SQ when using UPnP, then comparing it to files read from USB stick is the acid test. just remember to unplug the Ethernet cable when using the USB to get a valid comparison.

Having optimised my system and taken care to protect everything from RFI, as far as I can tell the SQ is the same from a USB stick and the network.  Before the RFI protection work though, the network sound wasn't as good as a USB stick.  However I live in an area with a lot of RFI, it won't be so bad for most people.  If you're unlucky, then RFI protection using clip-on ferrite beads may be necessary.

I already have the Audioquest Pearl cable, so I don't really want to fork out on additional cable.

The cable will be running down the side of the house, from the first, to the ground floor, and 2 feet above ground level. 

The more I think about it...phone cable, satelite cable, aerial cable, is all clipped to the outside of the house. I'm suggesting to place it in conduit, to protect it from the elements, which is more protection than the above cables have.

Ok, just to set some balance... Yes in most cases wifi will be less reliable than wired Ethernet, however as far as RFI then it becomes more interesting... The frequency of the main carriers of wifi are significantly higher than the clocks used in digital audio.. However on a 100 Mbps Ethernet access, the main carrier of the Manchester encoded signal is approx 31MHz. This frequency is far more sensitive for our digital audio clocks and also is more likely to cause intermodulation distortions with our audio circuitry, have a larger wavelength (about 9 metres) and therefore more likely  to cause interference with our audio and digital audio circuitry... No doubt why there is much interest in various boutique Ethernet cables that filter and tune this RFI...

So wired Ethernet .. Absolutely a plus for reliability and overall speed, ... RFI it's more evenly balanced .. And depending on implementation I feel wired Ethernet can be more liable to cause audio impacts than wifi.

Implementation is important and  the wifi module will in my experience typically consume more power than an Ethernet port interface.. Therefore disabling the wifi module will I suspect on many designs lessens the current loading on the PSU and almost certainly give a positive effect on audio or clocked digital circuits sharing that powersupply.

Simon

James...just to clarify, your Cat5e cable is clipped to the outside brickwork, exposed to the elements. Wind, rain, snow and the sun?

Hi Bert !

As I stated in one of my post, I had a good linear power supply lying around (check the HDPlex site) that was compatible with my Qnap HS-251 and so I tried it: after some time of use I can say that the SQ is not perceivble better as it was with the NAS connected to the standard PSU. But maybe mine is a subjective impression.

P.S. the NDX is connected to the NAS through a professional HP 48 port gigabit switch with a CAT 6 cable of good quality who is approximately 15 meters long and who is laid in a separated  line (well separatefd from the electricity line)

Yep. 

Thanks James