Balanced cables

Al, that makes a lot of sense to me, but both Warren Gehl (of ARC) and Kalvin told me that the amp employed a differential amplifier at its input. But they may have been reading off of the same cue sheet, which may not have been accurate. Although I've known both of them for 40 years, on this point I'm more willing to believe your theory as it is consistent with the amp's behavior. I never had the heart to to tell them that if what they said was true that a lot of performance was being left on the table. But who knows- maybe that will be part of the next iteration.

At any rate, that aspect of the amp's performance is well-known and acknowledged by ARC. So in the case of a balanced interconnect, if noise were able to impinge the cable, the amp would not be very good at rejecting it (in the old days this was often handled by an input transformer, which is usually very good at CMRR). So this would seem to make the characteristics of the cable more audible. For such an amplifier, I would recommend a cable that is double shielded.

At the risk of coming across as overly defensive (I own and love ARC gear), this sounds just a bit too conjectural/speculative. Warren Gehl to my knowledge does some very limited design work for ARC and is key in QC by reportedly listening to every piece of gear hooked up to his reference system of a Ref 6 and Ref 150se and some old, large Magnepans before the piece leaves the factory. It was, however, Ward Fiebiger who took over the reigns from Bill Johnson in the actual engineering/circuit layouts of ARC's top-level gear including the Ref series of preamps and amps. Now does that make a difference? Probably not. Surely Warren knows enough to answer the question being posed here. I actually tried to ask ARC the very same question, more or less. Guess what they said in response to my email? That I should contact my dealer! Very nice, huh? 

FWIW, I'm looking at my manual to my Ref 150 SE and it does not include a schematic and instead only has some specs, including that the output polarity is non-inverting with "Balanced input pin 2+ (IEC-268)"
Also interesting to me is this verbiage;
"IMPORTANT
Use the best available speaker wires and interconnects. Audio Research cannot emphasize this enough. As better components and systems are developed, it becomes increasingly important to avoid the limitations of inferior system interconnections"

Warren Gehl to my knowledge does some very limited design work for ARC and is key in QC by reportedly listening to every piece of gear hooked up to his reference system of a Ref 6 and Ref 150se and some old, large Magnepans before the piece leaves the factory. It was, however, Ward Fiebiger who took over the reigns from Bill Johnson in the actual engineering/circuit layouts of ARC's top-level gear including the Ref series of preamps and amps. Now does that make a difference? Probably not. Surely Warren knows enough to answer the question being posed here.

Warren has made a lot of contributions to the sound of ARC and little of it has been to circuitry- mostly vibration control, tube choice and similar. Bill hired him for his ears as he was/is very astute.

Ward (RIP) may have been influenced by the Italians who have since learned to let the company do what it does best. I'm not sure where your amp sits in this since it is still current.

I have seen some pretty expensive cables over at ARC (they are a 1/2 hour drive from here) so I've had pretty good reason to suspect that they didn't support the balanced standard (else you wouldn't need the pricey cables). Here is a nice bit about how balanced line works, from the Rane (a popular pro audio manufacturer) website:

http://www.rane.com/note110.html

@stringreen ,

Are you listening to lps, cds or both when you experience the metallic sound? If it's only on lps, (if you're still running the Classic platter), I'd suggest you try a nice TT mat...Funk Firm 5mm.

Good luck.

@fsonicsmith
Good points. Though, I’d assume most reviewers don’t have XLR on hand because only a small subset of gear actually *requires* it.

In the case of components which offer both XLR and RCA inputs and/or outputs, it’s probably worthwhile to understand the circuit topology. I don’t know what "pseudo balanced" means. But in many cases (such as in my EAR Yoshino gear), the balanced connectors are offered as a presumed convenience only. For example, my EAR 890 amplifier has balanced and unbalanced inputs selected by a switch. And when I switch to the RCA inputs, then the input transformers are bypassed. Transformers are probably the best way to convert balanced to unbalanced or vice versa, but they have a sound. So now if I prefer transparency, then I should use the unbalanced inputs. But if I prefer the additional transformer coloration, then I could use the XLR. One is not definitively "better", and the only thing to do is try it both ways.

One possible benefit in general of balanced is the elimination of any potential ground loops.