Dell 12v54A Server PSU for a car amp.

[phaseform]

Reading this thread it's mentioned that server PSU's aren't designed for fast current transients, I'm wondering if this could be overcome by putting caps between the PSU and a 12v car amp. I'm wondering as to a good source for high current, high capacity caps, as the ones I've seen for car amps appear to be largely marketing and not living up to specs.

[ConKbot]

CPUs have their own converters between the 12v psu and the processor, but then, so will a car amplifier. Keep the wiring beefy, short, close together to minimize inductance. As long as you're not expecting transients higher than the power supply output, it should be ok. 

You really need a lot of capacitance to provide any sort of surge capability.  5x 310F supercaps in series (62F total, $60ish worth if you get new Maxwell ones from mouser) would provide an extra 360W of surge capability for 1 second if of the voltage dips from 12.0 to 11.5V.  A 1F cap can provide 6W for 1 second with the same half volt dip.

So unless the car amp is lacking in input and output filtering on the internal power supply, a real possibility on cheap ones, and your long power cables have a lot of inductance (long runs in a car) a 1F electrolytic (even if it wasn't a cement filled fake) won't help with transient response/short bass hits for a subwoofer amp.

Edit: not suggesting actually using the super caps, just making an example. If you did, you'd need balancing resistors, and a startup/charging circuit  to keep it from overloading the power supply when you turn it on.

[NiHaoMike]

Latest CPUs change power state in tens of uS or faster. Unless you are a bat and listen to ultrasonic, I won't worry about it.
However, telecom PSUs tend to be more noisy compared to audio ones.

And automotive power systems are very noisy to begin with. If the amp is half decent, it will have plenty of filtering.