Does the phono sound better on its own, instead of run through the preamp? Or are you just wanting to take advantage of the XLR outputs?
8 responses Add your response
In short, you can not plug both XLR's and RCA plug into the XA60.5 simultaneously. If you plan to use the RCA plugs there must be a shorting bar between pins 1 and 3 on the XLR input connector. If you wish to use an XLR input the shorting bar must be removed. Reference the user manual. I have a X350.5 and it works the same way.
... But I assume that installing a fully isolating switched input on the Pass amps would address the issue you raised 'Liguy'... so, FWIW (and assuming you're willing to do, or have done, this relatively straitforeward mod): A few years back Naim Audio, considering how to wire two analog output connection options to one of their CD player models, did thorough listening evaluations between a simple -- and typical -- parallel connection, and switched outputs (off the same circuit take-out point). They reported that switched sounded better than having an unused connector effectively "dangling" in parallel off the output jack in use. Interesting... So that's the way they went. We might extrapolate from this to your situation.
If you look at the Aleph 5 schematic in which the RCA/XLR configuration is similar to his XA60.5. Having the connector hanging without a cable connected doesn't make much difference. All the jumper does is effectively puts a ground on one side of the input differential pair so you can use the single ended input.
O.K., once more... and geez, I didn't want to be the advocate for Naim's contention -- I don't even know if I believe 'em -- but they said the hanging bit DOES matter! That is exactly the point. I assume we are into the "low conductor mass, minimal eddy current argument" here: I checked the schematic, and the XLR's pins are not ISOLATED from the circuit in RCA mode, unless I'm cross-eyed. A ground path is not the same as isolation, nor is a bridge to nowhere (open circuit)! Most would SAY this set-up couldn't hurt -- and I guess that's your opinion, 'Liguy' [I am the inquiring agnostic here!] -- but Naim said, in effect, your common sense "wisdom" is WRONG. If that's crazy, blame their engineers; not me, the humble messenger. I wish I had never brought this up! I'm a detail
guy, I suppose... sorry. I just like the quest, you know? Because it's there.
On the plus side, you've got two pins connected through 10K resistors, which might ameliorate the conjectured problem somewhat -- I'd be guessing. On the negative side (of the argument), all the pins are firmly embedded in the XLR's not-great dialectric; even by conventional audiophile thinking, not so good. And speaker cables touching your carpet is supposed to be a horror. Note that the nearly $600 per pair XLR connectors being touted elsewhere in these forums has Delrin for the dialectric -- i.e., nylon... like your carpet.
Also keep in mind, these are the guys that held out so long for DIN
connectors... and who finally decided NOTHING out there was good enough, and so designed their own proprietary DIN-style connector! These folks are serious. Make your jokes -- I've got tubes and don't have a pew in that church.
So that's why I mentioned switches. So far, no one has piped in on Naim's actual assertion one way or the other. Me, I'm just curious.