$100-200 linear power supply

I think I am one of the few people not impressed with iFi power supplies.

I have had better luck at a fraction of the cost using medical grade power supplies from Mouser (don't buy this type of thing on Amazon).

If a battery did not fix your issue, then the issue is the amp itself. Battery power, while "pure," usually leads to loss in dynamics since they have a very limited discharge rate. Any 'haze' or color in the upper ranges should be from the amp.

At the end of the day, what you listen to is the power supply colored by the transistors. If you give it "perfect" power and do not get "perfect" sound, then the issue is the circuitry. You can attempt to mitigate this by using different filters in the DAC to roll off the upper frequencies or even use parametric equalization.

I think in you case, the best thing is to accept the limits of what you have, spend the least to get rid of the worst issues, and enjoy the music.

I am of the school of thought that one would be better off buying a better amplifier than sticking 2 or 3 times the cost in a power supply. It’s an $80.00 amp.

This is why:

the 4706 Gaincard offered excellent measured performance. In fact, almost all the measured problems I encountered can be laid at the feet of the Humpty power supply.

From the same review:

What is less good are the spikes overlaying the waveform at the signal’s zero-crossing points, which imply inadequate standing bias current in the Gaincard’s output stage. When RD writes about "a hardness or glare in the upper midrange and treble," I do wonder if that correlates with the presence of the high-order harmonics that will result from this behavior. Of course, RD also found that this character dissipated after a very long break-in period.

 

Lab 4706 Gaincard, 1kHz waveform at 22W into 4 ohms (top), distortion and noise waveform with fundamental notched out

@ericgale 

I am of the school of thought that one would be better off buying a better amplifier than sticking 2 or 3 times the cost in a power supply.

Sure, what amp would that be? It would help if you have heard this amp so you can know what type of sound I am talking about.