My local Naim dealer in Toronto (Robert Fulton at Stewart's Audio & Video) has been passing on his wisdom regarding dedicated spurs. Some of his recommendations are similar to what we read here on the forum, and some are a little different:
- Use at least a 20 amp breaker, although a 30 amp is preferred.
- Use shielded mains cable (BX), to reject RFI.
- Run two mains lines, one for the CD player and one for the amps. He believes the CDX spews garbage back onto the Mains, and the amps sound edgy and harsh if they're connected to the same line.
The first point is pretty typical.
The second is somewhat surprising, since Naim generally believes that using a shielded mains cable (the one between the wall plug and the component) is not a good idea. Perhaps the bigger gauge wire isn't affected as much, because the shield is further way from the current, so it won't cause much impedance.
The third point is most interesting. I heard his main demo system (CDX/102/NAPSC/Hi/250) before he had the dedicated lines, after when he was using one line for all of the gear, and then again when he had the CDX on a separate line. I definitely heard the same types of improvements that he did.
However, this is the first time that I've been told that the CDX dumps noise back onto the power line. I mentioned this to another friend who has a CDX and a bunch of test equipment. He checked and confirmed that the CDX does affect the quality of the mains lines, and that the amps sound cleaner when the CDX is on a separate spur (much to his surprise, I might add).
Therefore, it sounds like putting the CDX on a separate line is really a good thing. However, I suspect that it also depends on how your power is to begin with. The edginess that I heard at the store does not seem to appear on my own system. I am running 82/Super, though, instead of 102/NAPSC/Hi (all other components are the same).
Has anyone else experimented with this?
-=> Mike Hanson <=-
[This message was edited by Mike Hanson on THURSDAY 07 June 2001 at 11:49.]
Posted on: 07 June 2001 by Rico
On the old forum, where power was concerned, JV emphasised:
ONE. And only one. Even where the Lingo was concerned!
Listen to the music.
Mike, if you must tweak, unpack your Mana. You know it makes sense.
Rico - all your base are belong to us.
Posted on: 07 June 2001 by Dev B
>>>Separate line for CDX
I can't speak for Canadian households but over here one is best.
Dev
ps. why don't you get a proper Mains spike? but with your dreadful, tuneless speakers I am suprised you can hear the difference 
Posted on: 07 June 2001 by David Dever
quote:
1. Use at least a 20 amp breaker, although a 30 amp is preferred.2. Use shielded mains cable (BX), to reject RFI.
3. Run two mains lines, one for the CD player and one for the amps. He believes the CDX spews garbage back onto the Mains, and the amps sound edgy and harsh if they're connected to the same line.
Item 2 above is not borne out in my own experience (living downtown/downwind from the transmission baluns atop the Sears Tower in Chicago)--the metal shielding does affect the sound, making it a bit less lively, and a bit brighter. Likewise, rigid conduit itself is much more difficult to work with when running a dedicated spur.
I can't recall exactly, but isn't Romex (the flexible metal conduit stuff) limited to 15-20A circuits on this side of the Lakes? Anyone?
Item 3 requires more specific explanation--were these circuits on the same phase, or adjacent (opposite) phases of the mains run?
As any little bit of additional load will affect the system when there's too little current to go around, one would need to quantify the quality of power at the dealer's location.
Suppose though, that item 3 did make sense--perhaps this is the justification you were after to purchase an XPS, yes? 
Dave Dever, NANA
[This message was edited by David Dever, NANA on THURSDAY 07 June 2001 at 14:33.]
Posted on: 07 June 2001 by Mike Hanson
As I mentioned earlier, I think these statements are a little odd. BTW, this store is in a very commercial district, with lots of malls, neon, etc. clustered nearby. He's also in an old stripmall, which may not have good power feeds to begin with. They also sell and repair TVs, so who knows what kind of crap is on their mains.
Robert Fulton has been setting up Naim gear for a very long time, so I don't dismiss his statements without consideration. However, I've certainly heard many contrary positions here on the forum.
I suspect that I'll go for a single, dedicated circuit here in the house. Back in my apartment it usually sounded bad during the day, but it's sounded bad only once here where I checked, so I think my power is much better at the house.
-=> Mike Hanson <=-
Posted on: 07 June 2001 by MrI
When I found the CDX to effect the sound it was with two tests. I was using a dedicated 40 amp circuit and hard-wired Wiremold. I saw a change for the better when I put the CDX on a completely different circuit (but I would need to check which phase). The ground variance was less than .2 ohms between circuits. Also I seemed to be able to get about the same effect by daisy-chaining a second Wiremold onto the first and putting the amp and PSU on the first, the CDX on the end of the second giving the maximum distance between. I have stayed with this latter arrangement.
In regards to the shielded power line. I wish I had put one in having now found out that I have a ham operator in the neighbourhood. I am now auditioning series 5 gear which is apparently somewhat better at dealing with rf
Posted on: 07 June 2001 by Arthur Bye
Dave Dever wrote:
quote:
Likewise, rigid conduit itself is much more difficult to work with when running a dedicated spur.I can't recall exactly, but isn't Romex (the flexible metal conduit stuff) limited to 15-20A circuits on this side of the Lakes?
Dave: I think that Mike is referring not to rigid metal conduit, but to BX cable which is the flexible metal stuff with romex type conductors inside, usually with a crappy aluminum ground wire. I have purchased BX and standard Romex cable down to 8 guage which I believe is suitable for 40 or more amps. When you go larger than this size the conductor becomes multi-stranded and that may have a further impact on mains supply.
If you want to go larger you can and just use any insulated conductor and then buy some "Greenfield" to encase it. Greenfield is just sections of BX cabling wihtout the conductors and it comes in very large sizes. Not very attractive stuff though.
Mike: I tried a CDX/XPS on a separate spur once (out of phase with the other spur) and could not hear any difference. Didn't try it with a lone CDX though.
Arthur Bye
Posted on: 07 June 2001 by Rico
quote:
Try a ferrite ring around the cd-players mains cable.It will clean up the sound.
Yep. It'll take the music out along with it, too.
Rico - all your base are belong to us.