Can SMPS based preamps/amps sound organic ?

Jaybe, I repeat again - most of linear power supplies in power amps are unregulated.  I would bet that 100% of linear power supplies in class A  amps are unregulated.  Can you provide the link?  Sonore, you mentioned are 14W, unless I'm looking at wrong website.

Got a bit off track, sorry. The LPSs I referred to are external LPSs and not built into pre/amps.

But here is a good link to an article written by Nelson Pass touching on regulation and SMPSs in amplifiers.

https://passlabs.com/articles/power-supplies-commentary-for-consumers

And I admit I'm over my head on this so will sit in the sidelines. :)

kijanki,
Roger Sanders makes a regulated linear power supply for his Magtech amp which can drive his ESLs. Here is the link to that white paper:

http://www.sanderssoundsystems.com/technical-white-papers/161-the-magtech-regulated-power-supply-wp

And, i believe that he has a patent on this power supply architecture....

The complete Naim portfolio relies on their ability to provide various levels of linear power supplies. Primarily the quality of regulation decides the price of their PSUs

Bombaywalla, Thank you for the link, very interesting.  The only problem is that what they describe:

The digital control circuitry constantly monitors the pulsating waves from the regulator and the rail voltages. It will then make a decision to turn the coupling transistors on or off at each zero point to add as many or few pulses as required to hold the voltage constant.  

is switching regulator.  Any time something is completely on or off it is switching.  Idea of controlling number of full wave cycles is not new - it used to be called "Group Regulation" and was even used in such applications as quiet light dimmers.  The problem is, that power supply is still "linear" and in order to respond fast it needs low inductance capacitors.  The best you can get is "Split Foil" type, but it is expensive and still poor.  Adding parallel low inductance capacitor helps, but also creates resonant circuit with inductance of large main caps.

Their regulator is a step in right direction (switching), but why not use switchers?  Linear power supply switches anyway at 120Hz at max voltage.  Yes, not many companies use SMPS with class A or AB amps but some do (Rowland, Benchmark, Linn etc).  I don't understand term used in their paper "Linear Amplifier".  I've never heard it before.  I assume, they mean "not class D",  but class D is still linear (and not digital) in all respects.