My OCD would get the better of me here too… 
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As retired plumber I can solder, but only on 15mm, 22mm and 28mm pipe work! 
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A bit of pure deductive logic:
Can having unequal lengths improve the sound?
Is there any chance that changing some physical parameter will have absolutely no effect on the sound?
This leaves only one conclusion
A friend of mine had a Naim system supplied and installed by Billy Vee. The system lives on a rack to the left of the left speaker. One of the NacA5 cables is 4m and the other about 1.5m. The amp is ‘only’ a Nait 5i but I’ve always found it strange that they installed it like that.
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Having dipped a tentative toe into the speaker cable debate a couple of times, might I ask - as someone with no electrical engineering knowledge - why we consider only the cables in these discussions and why we don’t include the (presumably very significant) impact of the speakers? As they complete the ‘circuit’, and can vary dramatically in sensitivity, surely they are just as critical? Would, for instance, demanding speakers thus make your cable selection more critical than those that are easier to drive? Just curious…
Sorry Stilts, I’m not technically knowledgeable enough to give any meaningful answer there.
OK, here goes…
This is the closest description I can present without going into a shed load of maths! …
The most general main requirement for power amps is that the capacitance of the load isn’t too low. Too low a capacitance presented by the load causes higher currents to flow at higher frequencies, but these currents are also phase shifted. This reduces the output voltage of the amp and the feedback loop will, after a further short delay) try to compensate by increasing the drive to the output stage, however by this time the output voltage will have started to recover, so the output overshoots it’s target. This in turn causes the feedback to try to reduce the output voltage (again after a short delay, causing the voltage to fall too far - another overshoot. After another short delay the output starts to recover and the feedback again causes yet another an overshoot.
The amplifier either oscillates or at least suffered from insufficient damping at ultrasonic frequencies.
To help ensure this doesn’t happen, most amps have an inductor and parallel resistor in series with the output to the load (the compromise in the quality of the connection to the load is the trade-off for this protection).
The main requirement for Naim amps is that the load inductance is or greater magnitude than the capacitance, to stop the above situation. This is necessary as Naim amps don’t have a large high current inductor in series with the load, instead relying on all this inductance to be provided with by the speaker cable (i.e. they don’t make the trade off compromising the sound for greater stability into capacitative load when non-inductive speaker cables are used).
In the first case, if non-inductive speaker cables are used with a capacitative load, or high capacitance speaker cables are used, the amp remains stable. (High inductance speaker cables will still give stability, but may sound dull.)
With Naim amps, high inductance speaker cables are required for stability into capacitative loads (the inductance of the cable protects the amp for the capacitance at it’s far end), but high capacitance speaker cables (e.g. Litz designs) should NOT be used as there’s insufficient inductance in between the output of the amp and the capacitance presented by the cable. Only when the load is itself more inductive than capacitative are non-inductive (and low capacitance) speaker cables a fair choice for Naim amps; as few speakers give their FULL electrical specification it’s REALLY difficult to know if this is the case, so it’s unwise to use speaker cables that don’t have the specified high inductance.
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Thanks Xanthe, that’s very informative. What properties of manufacture make a cable either high/low inductance/capacitance? While I have your attention 
In essence:
All other things being equal, inductance is essentially proportional to the enclosed area in between the signal and return conductors.
All other things being equal, capacitance is approximately proportional to the effective lateral area of the conductors* and inversely proportional to the square of the separation of the conductors.
.* overall for many speaker cable geometries, this is effectively works out as being equal the the cross sectional are of the conductors!
Should the soldering iron bit be linear crystal oxygen free copper?
In general it should usually be plated with iron or a suitable alloy .
Sorry - I was just being silly.
Dare I suggest that’s a picture paints a thousand words??
Ultimately, though, it appears that there can be so many variables that - within reason - only trial & error will tell; i.e. does the amp run hot, do the speakers sound overly bright/flat etc. I guess…
But the speaker won’t reduce the cable’s properties, so the minimal recommended cable length (for given cable parameters) will provide a safe lower limit to which the speaker will only add (less or more depending on speaker)
That’s not strictly true. The speaker presents it’s own load in terms of capacitance and inductance. The cable properties themselves mean nothing to the amp on their own. The amp doesn’t see the cables and the speaker separately. It sees a single load of cable+speaker. As such if the speakers present a truly bizarre load, 3.5m of A5 might still be unstable if somehow a speaker presented a massive capacitive load and added very little to the inductance. The scales can easily get tipped in the wrong direction. Which is theoretically possible with non traditional drivers or crossovers.
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OK yeah, but in practical terms for normal speakers. Obviously when using some weird designs one has to consider the effects
Understood @Beachcomber, thankfully I am grateful that most reputable soldering iron manufactures make this decision for us otherwise we could end up with yet another 1000 post thread about something that doesn’t make any notable difference.
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