Can SMPS based preamps/amps sound organic ?

Jeff Rowland uses SMPS for low noise. That’s why he uses them in applications where efficiency is non-issue, like Capri preamp. SMPS got bad rap from crude computer applications but when is done right is extremely quiet. Most of linear power supplies are in reality primitive switchers that switch at 120Hz at the peak of the voltage causing transition noise that propagates thru the amplifier. In addition 120Hz ripple is difficult to filter out thus requiring big electrolytic caps. These cap, in series with the signal path (circuit closes thru them), are inductive and slow down response. Power transformer has to be huge at this low frequency. Modern SMPS switches at zero voltage/ zero current at frequency that is inaudible and easy to filter out (Rowland’s 625 SMPS switches at 1MHz). It has fast response time and is line and load regulated while linear supply in power amps is not. Huge transformer is replaced by small ferrite one that can carry the same power at very high frequency.
Benchmark replaced linear supply in their newer DACs with switcher while their new 132dB S/N ABH2 amplifier also has SMPS. SMPS can be quiet not only electrically but also acoustically being free of buzz and with AC/DC operation, often in wide range.

http://jeffrowlandgroup.com/kb/questions.php?questionid=145

Why to design complicated SMPS when the most of customers believe that it has to be big and heavy to sound good?  Small and efficient bring suspicion that something (sound) has to give.  In addition word "switching" suggests electrical noise.

But I can think of a reason a LPS may sound better in your home. One thing is a transformer will filter out or reduce incoming high frequency electrical noise where especially older SMPS will pass it through.

Modern SMPS often contain Power Factor correction module, basically a huge inductor and capacitor, making supply appear as resistive load but also filtering any line noise. They are also line and load regulated with fast response that will eliminate in tandem with supply capacitors most of the line noise. In contrast, most of linear power supplies draw supply current in short spikes of high amplitude that "travel" thru the power cord and pollute everything around. The only thing "linear" about "linear power supplies" is that they are unregulated. I would suggest replacing word "linear" with "unregulated" since they (most of them) operate as primitive unregulated switchers - nothing linear about it.

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.

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.

Bombaywalla, I'm familiar with class G principle of operation.  And you're right - their "invention" is pretty much class G. It does not matter if you switch signal or supplies - it is still switching operation.  Rowland (IMHO) is the leader again with unpopular, while great sounding choices.

Patent does not mean much (I have couple of them).  Patenting new principle of operation is practically impossible, so the most of people patent specific use.  You can come up with any weird stuff and register it.  Patent office does not check validity of the idea. They only check if it was used before - no matter how stupid.  The word "Patent" suggests originality.