Balanced vs. Unbalanced - What does it mean?


I have a McIntosh MC402, I am using the Unbalanced inputs - my dealer hooked it up for me. Everything sounds fine but I am wondering about the Balanced input. When do they get used? Does it sound different? Which is best?
cam3366

Try 'em out and see for yourself. of course, your source or preamp has to be likewise outfitted with xlr outputs.

Usually if truly balanced the back drop will be darker or quieter... less noise. There might also be a touch cleaner sound presented given the balanced approach. other's will say this with more technical insight.

If you feel such a change from SE to XLR will provide you night and day diffs, I doubt that notion will prevail. Albeit, it is likely going to be a noticeable one... again, if truly balanced.
I had an Ayre amp and preamp which I used for years with RCA's because I didn't think the more expensive balanced cables would make a significant difference. Then I got the audiophile bug and tried balanced cables. There was an obvious improvement, well worth the extra expense.
We need a better technical explanation. I asked and was given two different answers. One it just means that the signal is always kept equal between the two channels. As if centered if there was balance pot that made sure it was centered. with a dumb look-- like you know --balanced.
I thought it would always be balanced if you have no control. AS in the usual setting for a any option which is no longer worth making the signal path longer for. If you are thinking like a true audiophile.
As if the balance knob is alway dead center. Which what you got when the preamps and integrateds had a balance knobe and a defeat button/switch to employ. The balance is defaulted to precisely equal for both channels.
The other answer was that the signal is always kept grounded in essence with hand waving.... you know?? I don't! The expense and lack of xlr inputs on the first couple of amps has kept me using RCAs that are SE I guess. Although they could be SPDIF lurking in RCA clothes for all I know.
Where are the technophiles, bring in the technophiles.
The techies can tell you what it is but cant tell you how it sounds.As usual synergy rules and that is to be found in the arena,not on paper or cyberspace,YMMV,cheers,Bob
Balanced connections mean that there are two signal wires per channel, each carrying a different polarity of the same signal and twisted together. There is no ground, per se, as any ground lead is only to shield the wires and the two signal leads, only, are connected between the two components. The most significant result is that any RF or electrical noise picked up by these leads is effectively canceled because of the differential termination that subtracts one from the other at the (differential) termiantion. This will make for less noise in electrically noisy environments or with VERY long runs.

Unbalanced consists of a signal lead and ground lead.

In practice, there is no real difference unless you have unusual conditions such as RF noise and/or runs of many meters. My interconnects are 10 meters and there is no audible difference between balanced and unbalanced except that the XLR connectors on the balanced lines are more secure and durable.

Kal
I would add that XLR circuits use higher signal levels - so better signal to noise or more dynamic range.
Balanced circuits are needed when there is a noise problem. If using a preamp of suitable gain, running RCA shielded cable for 30ft. should be no problem. When Sheffield Lab did their recordings, they used a shielded coax cable to run from Wiley Chapel to the electronics some 300ft. And we all know how quiet and good those recordings are. I prefer the XLR connector, and use them with the +(2) gnd(1) or pin 1 and pin 2, and not use pin 3 (-). RCA's seem to stretch and get loose over time. I just use the two wire rca cable and put on XLR connectors. My preference is the USA made switchcraft or Vampire. Jallen
Thanks for the information so far.

Can I use RCA out of my preamp with XLR into the amp? Do such interconnects exist and if so, any recommendations? I am using a Linn preamp into the MC402.
See this paper regarding interfacing a single-ended preamp output to the balanced input of your power amp. It's a bit technical, but well worth reading. As you'll see on page 2 of this paper, and as JAllen suggested, an adapter cable can be used. But alternatively, for better noise rejection, a QUALITY transformer (such as the ones made by Jensen Transformers) can also be used.

http://www.jensen-transformers.com/an/an003.pdf

You can find lots of adapter cables and adapters here:

http://www.bhphotovideo.com/c/browse/Cables-In-Line-Accessories/ci/1667/N/4294549275

Here is one example:

http://www.bhphotovideo.com/c/product/133649-REG/Comprehensive_XLRP_PP_6ST_EXF_3_Pin_XLR_Male.html#features

More generally, concerning balanced vs. unbalanced, I'll add a few additional thoughts to the excellent comments which have been made.

Besides the noise immunity advantage of balanced interfaces, single-ended (rca) interfaces are far more prone to hum and ground-loop problems than balanced (xlr) interfaces. That is because a single-ended interface uses the shield of the interconnect cable to both carry the signal return current, and to connect the chassis of each of the two components together (which are in turn connected to both signal ground and ac safety ground). So any voltage offset or noise differential between the ac safety grounds of the two pieces of equipment will result in an extraneous current flowing through the shield, which the receiving component cannot distinguish from signal current. Besides sometimes causing problems which are difficult to troubleshoot (as evidenced by many threads here at Audiogon), that can limit your flexibility in providing separate filtering of the ac delivered to different components, and using multiple dedicated ac lines to prevent cross-coupling of, for instance, digital noise into analog components.

Also, it is important to distinguish between components which are "fully balanced," and those which are not. A fully balanced amplifier or preamplifier provides a completely separate signal path internally for each of the two polarities of the input and output of each channel. A component which is not fully balanced just has a differential input and/or output stage, but has a single-ended signal path internally. Your MC402 appears to be fully balanced, as indicated by this statement in the manual:

Exclusive Double Balanced Circuity: Each channel of the MC402 consists of two balanced power amplifiers operating in push-pull with their outputs combined in a McIntosh Autoformer. This double balanced configuration from input to output cancels virtually all distortion.

An amplifier which is not fully balanced would typically cost less, would not provide the (at least partial) cancellation of internally generated distortion which this paragraph refers to, and might actually sound worse with the balanced interface than with an unbalanced one, because of the extra stage which is introduced into the signal path at the input and/or output, to do the single-ended to balanced conversion. It would, however, provide some degree of rejection of noise pickup, which may or may not be important in the particular setup.

Finally, re long cables, it should be kept in mind that regardless of whether the interface is single-ended or balanced, if both the output impedance of the preamp (or other driving component) and the capacitance of the cable (which is proportional to length) are too high, upper treble rolloff will result. That's not a concern under most circumstances, particularly with solid state gear, but if the driving component's output impedance were say upwards of 500 ohms, and the run were say 30 feet or more, I would make a point of avoiding high capacitance cables (e.g., choose cables that are around 20 or 30 picofarads per foot, and definitely avoid those that are around 100 pf/foot or more).

Regards,
-- Al
Some electronics are designed single ended with balanced operation included so that the buyer would think that the component is a greater performer. The truth is that those circuits that are designed single ended with XLR options sound the same in either configuration. Circuits like those that are designed around a balanced circuit such as Ayre will greatly benefit from balanced operation, although single ended operation is available for convenience.
Not meaning to give Kal (Kr4) a hard time with this post, as his responses on this forum are hugely valuable and much appreciated, but I *am* surprised, Kal at your response here.

I remember quite well your excellent review of the Bel Canto PL-1A in which you noted that it sounds better through its balanced outputs. For about four years the PL-1A was my main source (your review being something that put me onto that unit in the first place), and I agreed with your review completely, including your pointing out that it sounds better through the balanced outputs.
The balanced line system was designed to solve (and very effectively) three different problems: noise in cables, length limitations in cables, and finally (IMO the most important thing to audiophiles) preventing sonic artifacts from cables.

IOW **if your balanced line system is set up properly** you will finally hear no difference between a cheap cable and a very expensive cable. The length will have little bearing on the sound either, plus of course you will have blacker backgrounds as there will be less noise.

Now **it does not matter how long the cable is**! If the cable is only three feet long there is still an advantage, due to the fact that the cable has no sonic artifact.

If you **do** hear artifacts (IOW if one cable seems to sound better than another) then your 'balanced line' system is not set up right.

Decades ago (over 50 years...) this stuff was figured out. All LPs were recorded using balanced lines, in many cases with 150 feet between the microphones and the input of the recorder. If the cables were a problem, we would all know it by now, but as our stereos improve, the merits of many vintage LPs continue to improve- the cables used to make those LPs were/are completely transparent.

To take advantage of balanced lines, the amp has to have real balanced inputs! Some amps have the connectors, but the input is really single-ended. If the circuit of the amplifier is single-ended, sometimes the balanced input is accomplished with an input transformer. This transformer has an artifact; IMO/IME you are always better off with a real balanced input.
Dgaylin-

I am not retracting my comments but it is certainly possible for a given component to sound better via one output vs. another depending on the design of that particular component. In general and in normal environments, there should be no difference between bal and unbal connections.

Kal
This is one of those threads that can go on forever as there is no real answer. As has been pointed out it is system dependent. There is little or no agreement among the most experienced designers and reviewers. Martin Colloms, who has tested about everything for 30 years has said that 95% of the components he tests sound better single ended and that balanced best use is in long runs in studios. BUT, he uses VERY expensive ICs. A recent article by a recording industry professional in HIFICRITIC mag. , which Colloms publishes, came down on the other side. The author maintained that equal results could be obtained with much cheaper cable with balanced. At the same time he pointed out, as mentioned above, that not all "balanced" are created equal and that standards about how it is implemented are very imprecise, a situation not unknown in other area of audio. He also recommends transformers in some cases. He notes that balanced seems to be popular in US and Japan but not Europe, which he finds strange. So the answer seems to be dependent on each system and user, another not unusual finding.
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I don't know or understand the difference and I really don't care. All I really care about is how either will sound in my system. However, I tried both single ended and balanced. Balanced sounds better in my system.
.
Thanks for the information everyone and Almarg - thank you for the links.

Has anyone compared balanced to unbalanced on the McIntosh MC402 Amp?
“Line-level” signal level for consumer audio equipment is nominally -10dBV (0.32V RMS). However, “line-level” signal level for pro-sound equipment is +4dBV (1.23V RMS). Simply put, pro audio gear is looking for a 14dB higher signal level.

Anyone who suspects that 14db additional signal level will likely translate into significant benefits in dynamic range would be correct (never mind the length of your audio cables). Most electronics does not perform as well at very low signal levels. Of course, it won't matter much for a hyper-compressed Green Day album but on a good recording you'll often notice a small or slight difference with balanced.

Also the "hum" that Al mentions is even more of a significant problem when using lower signal levels - not to metion the lack of shielding and the problematic grounding of chassis when using RCA. Serious audiophiles really should consider balanced before investing in things like resonator cups, as there is science as well as a long track record behind balanced XLR equipment.

Nevertheless be careful. Pro audio gear will often be too "hot" for consumer grade stuff and you'll get clipping unless you attenuate pro quality balanced signals when interfacing to ordinary consumer grade gear. RCA is ubiquitous ONLY because it is cheap and often adequate.
I should add to the mention of adapters and adapter cables in my previous post that although these are viable alternatives for interfacing a single-ended output to a balanced input (using an rca-male to xlr-male cable or adapter), interfacing in the other direction (balanced output to single-ended input, using an xlr-female to rca-male cable or adapter) should not be done with typical commercially available cables and adapters without careful investigation of whether the output of the particular equipment can tolerate having one of the two opposite-polarity output signals connected to ground.

Adapters and adapter cables used for that purpose will typically ground pin 3 (which on USA equipment carries the negative-going or "cold" signal polarity). Grounding that signal will result in improper operation or damage to the output stages of some equipment.

Regards,
-- Al
Shadorne - Not sure I understand all of your last post. Am I OK to use a RCA male output from my preamp and an XLR male input into the amp or do I need to include something else to avoid clipping? Thanks for the help.
It may not have been clear from the other posts, but there is zero advantage (other than the XLR being a better connector) of connecting the unbalanced signal from your preamp to the balanced input of your amp; there will be no noise rejection. You can use a Jensen output transformer to convert your preamp's output to balanced.

The signal level difference Shadorne spoke of should not be an issue for you assuming your components upstream from the amp are "consumer" models.

Here's another less technical article on balanced/unbalanced: http://www.bluejeanscable.com/articles/balanced.htm

and here's one on hum in unbalanced cables: http://www.bluejeanscable.com/articles/humrejection.htm
Cam -- No, I think that Shadorne was speaking in more general terms, and the issue he cited about overdriving consumer-oriented gear with pro-oriented signals is not applicable to your situation.

It would be a concern if the outputs of a pro-oriented source component, or a pro-oriented equalizer or processor, were fed into the line-level inputs or tape inputs of a consumer-oriented preamplifier.

In your case, though, you are dealing with a preamp-to-power amp interface (meaning higher full-scale voltage than consumer source component line-level), and with both components being consumer-oriented. Your power amp has an input sensitivity of 2 volts in unbalanced mode, or 4 volts in balanced mode. That will certainly not result in clipping or overdriving when being fed by typical components.

In fact, the opposite will occur to a minor degree if you go with the adapter cable approach -- you will have to turn the volume control up by 6db relative to where you set it when using the power amp's unbalanced inputs. That is because instead of feeding the amp with a balanced pair of signals that have equal amplitudes and opposite polarities, you will be substituting ground (0 volts) for one of those polarities, resulting in the difference between them being half as much.

The only negative effect that could conceivably have would be to increase background hiss slightly, but unless something is marginal in your system to begin with that will not be a perceptible effect. You can test that right now, in unbalanced mode, by simply turning your volume control up a little bit from where you normally set it (corresponding to a 6db increase, as best as you can estimate that), with no music playing, and seeing if the hiss level becomes objectionable.

Regards,
-- Al
True diff. balanced circuits use "common mode rejection" to reduce the noise floor of the equipment and increase signal to noise ratio. (not necesarly just line noise and RFI)

Some (many) components have XLR connections tacked on the back, but the circuits are not true diff balance designs and many times they may actually sound better just using the RCA jacks because the signal path is actually shorter.

Generally, the input inpedance is not the same for the XLR and RCA jacks, so things may sound different.
Almarg - Actully, Audio Research, at one time sold an active component just for converting from single ended to balanced (and the other way too). Did anyone ever buy one of these. (I think it was at the time of the LS5 preamp that only had XLRs and NO RCA jacks.)
It would be a concern if the outputs of a pro-oriented source component, or a pro-oriented equalizer or processor, were fed into the line-level inputs or tape inputs of a consumer-oriented preamplifier

Exactly. If you use a Benchmark DAC1 with the XLR ouput into a consumer grade preamp or poweramp then you will probably need to set the attenuator pad in the DAC1 to drop the signal level by 20db. (This is wasteful of the higher ouput capability of pro balanced lines. It is generally a good rule of thumb to use higher level signals to give you more dynamic range over the equipment noise floor. It may well be enough of a difference to be able to hear something very soft or 60 db down versus not hearing it at all...)
I'm not sure if this has already been noted here, but I'd like to clarify: You cannot be sure that an unbalanced output can be effectively run into a balanced XLR input merely by the simple addition of a physical adaptor. ARC gear will not work correctly in this set-up. That is why ARC sold their transformer.

IIRC, ARC's power amp protection circuitry will be triggered by the unbalanced input signal and severely limit the amp's power output. This is evidently a function of the protection scheme that ARC uses in its power amps. Other brands may (or may not) have similar problems. Probably best to check with the manufacturer.

Good Luck.

Marty
Best advice provided, IMO:
08-24-09: Blindjim

Try 'em out and see for yourself.

The technical discussion is educational, but for this OP, I'll wager listening is more helpful.

If a difference can be heard between running single ended versus running single ended to balanced using RCA>XLR adapters, then that's a positive step. The next step is to determine what sounds best *to the listener*. In the end, that's all that matters.

PS - IMO, there's zero benefit connecting single ended outputs (Linn) to balanced inputs (MC402). Might as well run single ended. But, try it both ways and decide for yourself.
Then, the next step is to determine what sounds best *to the listener*. In the end, that's all that matters.

I think we all agree on this but "try 'em out and see" is not helping to increase understanding. (I am sure that Cam will take this for granted - I am sure he is going to listen and see)

However, a listen and see kind of approach is exactly how sonic properties become associated with interconnecting wires when the root cause is equipment related or impedance matching or mistaken volume level matching or any of hundreds of possibilities that have nothing to do with the purity of the copper. Creating a new myth every month, week or day.

Sometimes (perhaps often) degradation to a musical source is not always inherently obvious to even a trained listener (small amounts of compression and distortion can even regarded perceptively as pleasant or an improvement). This is why there are companies like Audio Precision otherwise we could ALL, as an entire industry, simply "try 'em out and see". Sadly "try 'em out and see" is the only approach that some manufacturers actually practice. This is how you end up with nice sounding products that do not reproduce the source material with much accuracy (measure badly but are claimed to be SOTA).
In the end, a system built according to correct theory may still sound like crap compared with one assembled by someone with less technical acumen, but with better "ears" (i.e., judgment, taste, experience, etc).

And that's the irony of the whole discussion.
Bob Reynolds: It may not have been clear from the other posts, but there is zero advantage (other than the XLR being a better connector) of connecting the unbalanced signal from your preamp to the balanced input of your amp; there will be no noise rejection.

TVAD: IMO, there's zero benefit connecting single ended outputs (Linn) to balanced inputs (MC402). Might as well run single ended. But, try it both ways and decide for yourself.

In principle, I don't think that is true, gentlemen, although of course in practice whether it would yield a net improvement, a net degradation, or no net change is dependent on the specific equipment and the specific noise environment.

See Figure 2.1 of the Jensen paper I linked to earlier, and the words immediately under the figure:

http://www.jensen-transformers.com/an/an003.pdf

Note the statement that in this example CMRR will be "only 30db at 60Hz." However, 30db rejection of common mode noise (at least at the power line frequency) is considerably better than no noise rejection.

Basically, by using the adapter cable into a balanced input you are still driving a balanced differential input stage with a cable whose construction provides symmetry between the hot and cold signal lines. Therefore noise pickup in the cable will tend to be closer to equal between those two lines than between the shield and the center conductor of an unbalanced interconnect, allowing the differential input to still subtract out that fraction of the noise which is picked up symmetrically.

And note in Figure 2.1 that currents flowing in the shield of the interconnect due to voltage differentials between the chassis of the two components (caused by offsets in their ac safety grounds) will not be sensed by the differential receiver stage, while they definitely would be by a single-ended input stage.

Shadorne: However, a listen and see kind of approach is exactly how sonic properties become associated with interconnecting wires when the root cause is equipment related or impedance matching or mistaken volume level matching or any of hundreds of possibilities that have nothing to do with the purity of the copper. Creating a new myth every month, week or day.

Very well put! And I'll add that both the op and Mechans specifically seemed to be asking for technical explanations, which I think have now been provided and which, while obviously not being the final determinant of what is best in any given system, can help prevent going down the wrong path and even blowing up equipment (as cautioned against in my second prior post).

Regards,
-- Al

08-25-09: Almarg
...although of course in practice whether it would yield a net improvement, a net degradation, or no net change is dependent on the specific equipment and the specific noise environment.
Thank you, Almarg, for underscoring my point so well.

You gotta try it and listen. One method may sound better than the other. Maybe the better sounding method will happen to follow correct theory. Perhaps the better sounding method will not follow correct theory.

In either case, go with what sounds best.
This is how you end up with nice sounding products that do not reproduce the source material with much accuracy (measure badly but are claimed to be SOTA).
Shadorne (System | Reviews | Threads | Answers)
To the customers of this equipment, nice sounding is everything.

You may not be a customer for this gear, but that doesn't make the nice sounding gear, or the approach used by the company to achieve the nice sounding gear, any less valid than the gear you choose for its ultimate accuracy.

There are those who will choose Bryston (i.e. accuracy) over VAC (i.e. nice sounding) every time, and there are those who will do the opposite. Who is to say what is correct for each individual?
To the customers of this equipment, nice sounding is everything.

Good point. I think one needs to be aware of both valid philosophies and make one's choices accordingly. I can't tell where the OP's preferences sit but hopefully both the technical and non technical advice will be helpful.

I guess all I am saying is that "listen and see" may not get to nirvana for everyone...for some it could be the holy grail while for others it may mean getting lost in a forest of near random equipment flipping/experimentation in order to get the nicest sound.
..."listen and see" may not get to nirvana for everyone...for some it could be the holy grail while for others it may mean getting lost in a forest of near random equipment flipping/experimentation in order to get the nicest sound.
Shadorne (System | Reviews | Threads | Answers)
There's no question that some basic knowledge is helpful to avoid tossing darts randomly.

Hasn't this been a learning process for you? It certainly has been for me.

Nevertheless, I believe there's no substitute for listening, and for tuning a system according to one's tastes. Haven't you done this, or have you stopped experimenting because of your belief in engineering and specs (no disrespect intended here...an honest question...)?

Let's be honest, the OP's question as it relates to his system is not particularly complicated, and neither is the answer. There are some well intended, and very thorough answers in this thread that go way beyond the scope of what's required to help him.

With deference to Shatern and others herein, I would submit the best resource we have in the final analysis is to “Try ‘em and see for yourself” Unquestionably.

To make a beleaguered and contested thread still more monotonous, I’ll re-emphasize the more practical aside. …and this time keep my laptop plugged in.

AS sensible as it is to school our minds to the various equipment designs, so too should our ears be as well, educated. Notwithstanding this note I feel we have at our disposal remarkable testing apparatus even without being so necessarily informed. It is a fundamental prerequisite to pursue this hobby, just as is sight for the pursuit of printed text.

As long as one can initially determine notable differences as they stroll the confines of their local high end audio dealerships, moving from one outfit to the next better positioned one as they go, they are armed sufficiently enough.

Regardless the system under construction or now complete, the deciding factors for the effort has been the perceptions of the owner themselves, and via most laudably their own hearing abilities.

One has but to be able to discern between the 4 types of systems:

Uh… I’ll pass

Now that ain’t bad at all!

Take a check?

Or the more profound…
Oh… my… God! (or explicative of your choice)

The latter by it’s very nature usually precludes me from asking about the finances without laughing… or crying. Depends on the mood.

If the capacity for such divination is at one’s disposal, and is accompanied by some modicum of good sense, and the financial wherewithal to further the process they are on their way! Therapy might well be included in the budget too. For some however the machinations of the hobby are sufficiently therapeutic.

Regardless where we find ourselves on the scale, our own auditory abilities remain the sole litmus test as deciding good, better or best, irrespective of the designs we follow. Flea power or goliath, glass or sand, one signal path or the electronic dissimilarity of two, so long as more often than not, better and not different is followed, improvement is the result. No matter the philosophy one subscribes too.

I had an all BAT power train a while back. Balanced Audio’s Victor K applies a purely balanced approach to both his tube designs and his MOS FET SS designs. I used a combination of tube preamp and SS amp. Used XLRs to connect them ultimately. At first they were so attached using SE cables and adapters. I heard several xlr cables before deciding on one particular set. The XLR to XLR attachment was better sounding once done that way over using SE + adapter.

My source however was always SE + adapter into the purely balanced preamp.

I sold the preamp, and moved up a few notches to a SE tube preamp I felt sounded better. Naturally the new SE preamp had to use an adapter to connect to the amp. I used those supplied by BAT to do that. Even had my fav XLR cables converted to SE.

The result was #3 of the aforementioned levels of system performance IMO. In truth I should say it as IME…. Or In My Experience. In my own house and over many of those rigs I’ve heard at dealers. I sold all of that system save for some accessories and the preamp, and now have IME, one that yields a far better presentation. Better across the board? No. Just better overall.

Through this trek hearing was first and foremost the piper which solicited me to change and improve upon various components. Curiosity played a role, some wisdom was prevailed upon and my wallet presided over the whole of the affair. The latter at times being ignored, usually reaffirmed it’s voice by planting the detour sign which pointed me back to good sense and the inherent financial reality of each move.

Hearing too accounts for as much of the rhetoric around here as does anything else. Consequent professions of cabling worth or worthlessness. Power line accessories or their lack. Even tonality impressions of brightness, recession, fatiguing sounds, can be on a per basis debate and the end answer is held by the owner of that rig. No one else.

True too a consensus of viewpoints could be used to support one approach or another as long as the taker of the poll is capable of living with the results and not their own preferences.

I doubt seriously, very seriously anyone here has said “no” outright, to a thing they felt sounded better because some review or spec sheet said the numbers do not support it’s sonic abilities.

Have you ever heard someone say, or thought yourself to say, “Nope. I simply can’t buy that piece, Mister. It sounds great but the specs aren’t sufficiently adequate. Thanks anyhow.”

I think you’ll find that statement right next to the ones saying “Oh My Goodness” systems are free while they last.

We are by nature, more often than not, predisposed to overkill. Pedantic. Anal. Just plain picky. With occasionally the dog ego firmly attached to our heels, rather than nipping at them while we ascend our ‘hills’, as ol’ Frederich N. warned us about some decades ago. From it all and despite it too, now and then, is the very place that holds the involvement, excitement, deliberations, and consequent ‘fun’ one can derive from our hobby of choice. To limit oneself from experimentation or investigation on an end user level, the accumulation of knowledge and hence a better defined approach will cease. We will then wear, the ‘blinders’ of the unknown and untried. These muted and veiled oracles are then our guides, and our own ignorance then, the sole bar to our increase.

Certainly there are more congruent or amenable connections in how we interface our gear. The maker of the gear should be foremost in deciding which electronic path is best in those regards.

Although there are indeed some fascinating new twists on older themes now erupting from high end audio component manufacturers, how pieces are integrated one to another remains our own enterprise. Many are surely robust enough to afford several sorts of connections, and the best path will always be realized IF some personal trials are endured. Sometimes performance increases are not as constricted to only one way…. So long as human perception is handing down the verdict alternative means can be at least interesting, and at times profound.

If however we don’t “Try ‘em and see for ourselves”…. ‘we’ won’t really ever know fully the answer best fitting our particular & often unique, circumstances.
All - thanks again for all the expertise.

It appears there is no damage that can be done to try an RCA male output from my Linn preamp and a XLR male input into the MC402 amp. I can try it relatively cheaply with the cables in the links provided above by Almarg and see how it sounds for myself!
Nevertheless, I believe there's no substitute for listening, and for tuning a system according to one's tastes. Haven't you done this, or have you stopped experimenting because of your belief in engineering and specs (no disrespect intended here...an honest question...)?

You always have great points, Tvad. However, this thread belongs to the OP and is not about me.

As you correctly point out, I already said far more than my two cents worth on this thread - so I'll leave it at that. I agree with you that the OP should simply ignore what is not helpful - too much of it from me, unfortunately.
wikipedia link: http://en.wikipedia.org/wiki/Balanced_audio
Al, regarding Fig 2.1 in the Jensen paper... Thanks for pointing that out. Note that they require STP, would the same argument apply if using coax (and short pin 1 and 3 of the XLR together)? I would think much less effective since the noise level would be higher in the shield than the center conductor. So there would be residual noise in the signal after the differential input.
Yes, that sounds right, Bob. An adapter cable built with coax would provide much worse noise rejection than one built with shielded twisted pair, because of both the lack of physical symmetry between the two signal conductors, and because of the need to tie pins 1 and 3 together, to provide a connection between the chassis of the two components through the shield. That in turn would amount to a similar situation as a single-ended interface, in which inter-chassis ground-loop currents flow through a common path with signal return currents.

Which raises a good question about how typical adapters are designed internally. I'm not sure what the answer is.

Best,
-- Al