Thanks Keith, that was a clear explanation of the 2.
Now you might have me on the DAC, my PWD only uses a single Wolfson WM8741 chip and only has one single power supply. As far as I know it's a multi-channel capable DAC chip and its balanced outputs are true, but both channels are indeed coming from one chip and one PSU.
After that though, I think I got it. I've got a fully separated powered headphone amplifier, Audio-gd Phoenix, then another separated powered pre-amp, AMB a20, then I've got in fact 2 speakers from you guys, the Emotiva Pro Stealth 8s. Those are active and have no shared connections, so they're essentially each powered by their own mono block amplifier. Then all of this is connected using XLR, balanced connections.
I never fully thought to include my DAC in the Balanced Device vs. Balanced Connection part as newer age DAC chips seem to support balanced implementations internally, without requiring multiple chips like older R2R ones. And when using multiple chips there seems to be more motivation to have separate power supplies for each channel, like in my long time love affair Audio-gd Master 7. So besides my DAC and other new age DACs, I've always made sure to pay attention to the Balanced Device vs. Balanced Connection part. I don't like amps or pres that have balanced connections, but aren't internally balanced. It seems kind of fake to me. I appreciate your explanation of it though and can see that by adding a balanced connection to a non-balanced implementation amp they can try and take advantage of how balanced connections transmit singles.
The last part of your explanation did open up what I wondered about adding balanced connections and the potential value of it, even on a device that isn't internally balanced. I guess that starts to get a bit confusing when we're talking about the vintage amps and receivers I mentioned that do have dual-mono(individual PSU per channel), but that likely do not have isolated, floating grounds per side.
Also like PhoenixG said above, using better shielded RCA cables may help, but I was hopefully looking at extending the system I've already built. If there's no other way, then this will be my way and thank you PhoenixG for telling me of your success with it.
Just to make life even more..... interesting.....
The Wolfson 8741 is a stereo balanced DAC - which means that each Wolfson 8741 has a stereo pair of balanced outputs. However, you can also operate each Wolfson 8741 in "mono mode"; this is an even more special mode where you "cross connect" the two channels on the chip into a single mono channel with slightly better specs (very slightly; the S/N is about 3 dB better). The downside is that this requires more parts, is more complicated to design, and uses one DAC chip per channel instead of one for both channels.
What you also need to understand is that the whole concept of balanced - in the context of improving audio quality - only applies on the analog side of the DAC. The numbers going into the DAC aren't "balanced" - and there would be no benefit to their being so. (You can send a stream of numbers over a balanced connection, and you could even create a dual-stream of "balanced numbers", but they would be no more accurate than a single stream of numbers, so there would be no benefit at all. The whole idea of balanced analog signals is to cancel out errors, and digital numbers don't have errors, and so nothing to potentially cancel out.)
Now, you mentioned power supplies ..... and that is yet another context for the term "balanced" - with a whole extra set of meanings. With most tube amps, and with many
VERY early solid state designs, the amplifier was run from a single power supply (perhaps ground and +70V DC for a solid state amp). Because the output voltage could only range between 0 V and 70 V, but a speaker requires AC voltage, this type of design
REQUIRED an output transformer or output coupling capacitors. This sort of design is properly referred to as "single ended", and some folks referred to more modern designs, which ran off of dual power supplies (maybe +50 V and - 50 V), as being "balanced", or "differential". Modern designs are also often referred to as DC coupled - which automatically implies that dual supplies are used. (There are a bunch of names, depending on the context, and most modern solid state amps operate this way. The exception is bridged designs, which can run from either a single or dual supply). So most modern amplifiers run off of "plus and minus" power supplies.
With power amplifiers, where the power supplies are asked to deliver a lot of current, there is also the possibility that the current drawn by one channel will cause the other channel to distort. This is why monoblocks are considered to be better (because each channel is entirely separate - so each channel has its own plus and minus power supply). There are also stereo amplifiers where each channel has an entirely separate power supply, and the degree of separation may also vary; some amps have totally separate supplies for each channel, others may share a transformer, but have separate rectifiers and filters. (Note that a stereo "dual mono" amplifier requires
FOUR separate power supplies, a plus and a minus for each channel.)
Yet
ANOTHER factor is that some devices - like DACs - may have multiple sets of power supply sections for different purposes. This is especially typical for DACs. Digital circuitry tends to draw power in very short sharp pulses, which, in turn, can feed noise back into the power supply, which may then introduce noise or distortion to other parts of the circuitry. Therefore, it's usually better if you have separate filtered power supply sections for the analog and digital circuitry in a DAC. In fact, because the voltages at certain points in a DAC are super-critical, it's not unusual for a high-end DAC to have five or more separate power supply sections, each with its own filtering, with especially good filtering on the more critical sections.
Whether the term "balanced" is misleading or not is mostly a matter of context. Historically, in the days of tube equipment, very little equipment was internally balanced (although "push-pull" is a form of balanced design). However, because of the higher operating impedances of tube equipment, the connections between equipment were very sensitive to picking up hum and noise. Therefore, in the old days, most pro tube equipment used small signal transformers at the outputs and inputs to "create" a balanced signal for connection purposes. Good quality transformers worked very well for this, but were quite expensive, and so a good quality balanced input or output was considered an important premium feature on pro equipment - and one that you often paid a lot extra for - even though nobody even asked whether the rest of the circuitry was balanced or not (and it probably wasn't).
The thing you really need to keep in mind, though, is that all of this is done in the service of performance. (For example, if your DAC device has a S/N of 110 dB, which is excellent, it really doesn't matter if the Wolfson chips inside it are connected in the mode that gets a S/N of 125 dB or the mode that gets 128 dB. In a DAC, how well the power supply is designed, and how carefully the circuitry is laid out, will usually make much more difference than which mode on the chip is used.) If you have an unbalanced connection, and it's picking up noise, then switching to a balanced connection will probably help; and, if you're just putting together a system, using balanced connections to begin with will make it less likely that you'll have a noise problem; but, if you have unbalanced connections, and they're dead quiet already, then switching to balanced connections is unlikely to make any difference. Likewise, all else being equal, a balanced design may have lower distortion, but all else is rarely equal, so all that really counts in the end is the performance itself (it's quite possible for a well designed non-balanced amplifier to perform better, and sound better, than a balanced one that is less well designed).
