AN Niobium versus Tantalum resistors?

I am passing on naked resistors due to a point Takman brought up in their papers.. which is that naked is going to be a victim of induced current, which means magnetism.. this is the same reason Furutech has special grounding and demag in their connectors. Those competing magnetic fields are a no-no if you are going for rock bottom noise. Which I am in this application. Also... Takman pointed out the bodies can be a point to add vibration countermeasures.

not trying something on the basis of what you read in a paper published by a competitor, is rather unsound practice IMHO. Until you have heard a naked Vishay z foil replace another resistor in the direct signal path you can not begin to comprehend what they can do.

As I stated before, they are not a panacea, and must be used judiciously as their utter transparency can prove too ruthless and become overtly clinical when used exclusively.

In my Khozmo passive, the shunt resistors are the Takman REY metal film resistors and the single fixed series resistor in each channel is the Vishay z foil naked resistor.  As described by PW,

"their utter transparency can prove too ruthless and become overtly clinical" 

This becomes a personal choice but they are revealing for sure.

Regarding the Amtrans AMRG resistors in my Hattor BIG preamp, I believe they offer a couple of levels of resistors - mine are the black carbon film resistors.  All I can say is that they sound very nice with a good balance of detail and musicality.  The big Audio Note Silver Tantalum non-magnetic 2W resistors I used to replace the Shallco VC in my buffer also sound very good and seem to be well-balanced.

My favorite combination is using the z-foils in series positions and the AN silver tantalums in shunt positions. The higher wattage silver tants sound a bit richer but don't fit everywhere. 

I haven't tried the Niobiums. 

Takman's take on induced noise makes sense with the naked Vishay, but then, induced noise would predict lower transparency, resolution. I believe pretty universal experience TX2575 highest resolving, transparent resistor. Issue with these, wattage and lack of flavor, as previously noted these won't supply your needs.

In any case I'd like to hear your impressions of these resistors if you decide to try.

 these won't supply your needs

excluding compoents from consideration based on pure speculation made on the basis of what you read is rather unwise IMHO.