Help...are linear power supplies worth the expense for lower noise floor

Depends on what linear supply. I use CLC filter, then Jung super regulator, to feed a fet/jfet shunt regulator to feed dac digital and analog stages.

John Curl uses CLC filter then 3 terminal regulator, then shunt regulator, then local cap multiplier.

The best products use multiple stages of different linear regulator types.
 
If the Switcher-Type PS is used:

- It should operated a a frequency that is well-beyond the audible range and several times beyond the highest Sampling Rate used within the DAC
- ALL High-Frequency circuitry should be separated from / isolated from / shielded from any sensitive Analog Output-Stage circuitry

In the end, however, methinks that it would be easier to prevent "cross-contamination" from Linear sources where the highest frequency being introduced is the Primary Line Frequency and any harmonics of that.

Either way - do what Mr. Pass did with most of his Pre-Amps:
Keep the higher-Voltage stuff in a SEPARATE, shielded enclosure and keep it away from any sensitive analog circuitry. There's nothing like DISTANCE to keep Mutual Inductance at bay...