Actually, you've hit on a few good points, and missed a few (and I can't speak for Gene's reasoning).
Linear power supplies from decades ago were remarkably reliable... and transformers themselves pretty much last forever.
However, electrolytic capacitors do have a limited life expectancy, and modern ones are much more compact, and more reliable in the short term, but may have a somewhat shorter overall service life.
Early switch mode power supplies, while delivering excellent efficiency, were rather complicated, and somewhat unreliable.
However, while modern switch mode power supplies have gotten both more efficient and more complex, they have also gotten MUCH more reliable.
Regulated power supplies behave differently than unregulated power supplies in a number of ways.
In terms of performance, within their intended operating range, regulated supplies are far superior - and this has always been the case.
A typical regulated power supply delivers exactly the specified voltage over its entire operating range - and with very low noise.
The ONLY reason most old-style power amps use unregulated power supplies is because large regulated power supplies tended to be very expensive and inefficient.
(Regulated linear power supplies also generate a lot more heat - and so need either big fat heat sinks or fans.)
As a result, regulated linear power supplies have traditionally been used in critical locations, and where low power levels are involved, but not in places like power amplifier output sections.
(Most preamps, and the driver circuitry in many power amps, use regulated power supplies... just not the output stage.)
The bottom line is that, if you're going to operate an amplifier within its rated operating range, a regulated supply will deliver cleaner and more consistent power, and so better and more consistent performance.
However, if you have a somewhat under-powered amplifier, and plan to operate it right on the edge of its capabilities, it's performance will tend to "degrade more gradually" when you overload if it has an unregulated supply.
This is why unregulated power supplies made sense back in the days when adding regulation was expensive... and amplifiers were relatively low in power... and so were often operated at the edge of their operating range.
With modern amplifiers, plenty of power is available at a reasonable price, and they are usually operated within their rated limits, so a regulated supply is a much better choice.
Incidentally, as it turns out, while adding regulation to a linear power supply is complex and expensive, regulation is INHERENT in the design of most switch mode power supplies.
(So, unlike with a linear power supply, where you may choose to add regulation or not to, with an SMPS it's just part of the overall package.)
As for the amount of smoothing you get from a particular capacitor value.....
The ability of a capacitor to filter or reduce noise depends on the frequency of the noise involved...
Switch mode power supplies operate at much higher frequencies than linear power supplies with transformers powered directly by the the 60 Hz line voltage.
Because of this, the smaller capacitors they use actually provide FAR more filtering than the giant capacitors used in linear supplies.
(Our SMPS operates at around 1000x the frequency of a line powered linear power supply... making the "little" capacitors it uses about 1000x more effective at filtering).
But, beyond even that, a regulated power supply uses active circuitry to remove even the tiny bit of noise that the capacitors don't filter out.
It is absolutely true that, in the very early days of the technology, some poorly designed switch mode power supplies leaked their own flavor of nasties.
(And, to be fair, that can still happen with a poorly designed one.)
However, for the most part, that's ancient history.
(At best, if you doubt the capabilities of an amplifier's designers, you can fairly say that "linear power supplies are simpler to design and harder to screw up".)
But, yes, as someone suggested, for our designs we are going to choose the components that deliver the best performance and best reliability at the lowest cost.
(We don't want to throw away money any more than you do..... )
With the amount of power required by our XPA Gen3 and XPA-DR amps, a regulated switch mode power supply delivers the best combination of reliability, performance, and cost.
(And part of that is due to the fact that, being lighter, they cost less to ship, suffer less shipping damage, and are easier to handle and install.)
And, with our lower-powered BasX amps, for now it still makes sense to use transformer-based linear power supplies.
(The transformers they require are smaller, lighter, and cheaper... and deliver sufficient performance to get the job done very well.... so, in that situation, the added complexity of a SMPS isn't justified.)
The real trick is to select the right components for the job.
If you want to ogle big capacitors...
This one is about the size of a soda can...
It's rated at 3,000,000,000 microfarads (3,000 Farads)...
It can deliver around 9,000 Amps of current into a short circuit...
And you might well find a few of them in the braking system of a modern electric car...
(It also makes a pretty good paperweight)...
But it won't do you much good in an amplifier...
I wonder why this thread died. I'll give you my two cents. I think Gene (audioholics) prefers the linear power supply because I think he deems it more robust in power delivery vs. the switch mode power supply. Also, we don't have long term reliability data on these newer power supply designs. If the newer regulated power supplies last only ten years vs. 20+ years for linear power supplies this is going to have a feeling of cheapening the brand to save a few bucks. Plus, I'm a believer that more and better power caps in the supply smoothens out the electrical nasties a bit more and maybe this is another issue that gene has with the regulated power supplies. Flame away.
