How important is a Linear Power Supply Versus a Switcyed one?

Both are switching producing high frequency noise, but SMPS done poorly can be really bad, much worse than linear PS. On the other hand SMPS can be much quieter than linear PS if designed for low noise (zero current, zero voltage switching). Jeff Rowland uses SMPS even in preamps, where power losses are insignificant (where he used batteries before). Benchmark reduced noise by 10dB in DAC2 by using SMPS instead of linear PS, they used in DAC1. They also claim that such low level of noise wouldn’t be even obtainable with linear PS. If Sutherland offers this option, then linear PS is probably better, but I would look for reviews, or check return policy. It is always possible that they offer this option only because people demand it (SMPS has bad rap from crude, very noisy computer PS).

Any power supply introduces noise.  Linear PS is also switching (at max voltage).  The question is how much noise?  They had to have a reason to implement SMPS.  Switchers are usually used for their efficiency when high currents are required or for size when Linear PS takes too much space (wall-warts).  It is neither case so I thought there was a third reason - they can be designed to be extremely quiet, much quieter than Linear PS.  Otherwise why do it?  It is more expensive and more complicated than Linear PS, that has just few very cheap components.   There must be a reason.  Phono stage has RIAA correction that amplifies low frequencies.  It is +20dB@20Hz and likely +12dB@120Hz.  It is likely that it is also sensitive to low frequency power supply noise (120Hz) - common for Linear PS.

I don't know.  Perhaps SMPS is in standard production while LPS is not (requires modifications).