AN Niobium versus Tantalum resistors?

@pesky_wabbit I very much doubt the Z foils will deliver what OP desires in this particular case, reason I suggested Takman carbon films over Z foil.

And my suggestions not based on pure speculation as you speculate in regard to my experience. I have in fact been using the Z foils for years, many in my Merlin BAM, in previous dac, in former phono stage, in Art Audio Carissa Sig, in my present 300B monoblocks. So, plenty of experience, again, I doubt these will give OP what he desires. Also, wattage will be of concern, TX2575 just over 1/4 watt, yes, you can stack for greater wattage capability. In the end I believe OP is on correct path, he's done due diligence here.

Caddock MK132 have the signature the OP is looking for.  These are discontinued, however their replacements the MK232 should fit the bill as they share the same construction and have undergone only minor changes for Rohs compliance.

I've heard many things about the Z Foils and the Takman paper regarding their design is a logic aligned with many experiences I've had. We all have to prioritize based on the synergies and brands that resonate with us. In a perfect world, I would love to try them. Absolutely the only way to know anything for sure is to try it yourself.

If the AN resistors are too euphonic or feeling too inaccurate, I might go to the z-foils. Just when I think I master the logic of my DIY, I will get shocked with a failure and go searching in new territory :) Isn't that the truth?

Regardless..doesnt sound like too many people have tried Niobium.

doesnt sound like too many people have tried Niobium

think the price has scared a lot of people away. Would be most interested for you to post your findings 

I spoke to AN again, and they refused to offer qualitative remarks, saying it all depends on the balance and they do not use all Niobium or even all Kaisei in their equipment. Not surprised there. Still, I am placing my order.

I finally found a review, google-translated from Polish :

Tantalum resistors, such as several versions of Audio Note or Shinkoh, sound sweet, dynamic and slightly rounded, especially in the mid-bass. The relaxation of these resistors can take away too much coldness and sharpness, or unnecessary tension in the sound. Bold bass adds bulk to the sound when it is too thin and contoured. The voices move forward and fill. Their disadvantage is the lack of the deepest bass and excessive sweetness.

Rikens play super neutral and have deep bass. The mountain is resonant. If the source is too sharp, it may sound too lean. With a well-balanced system, this is the best choice.

Z-foil pulls out teeth during the burn-in process, then it is very neutral. Great for shunt volume attenuators.

Takman REX is bland and neutral.

You can write for so long, but we have to focus on AN NIOBIUM 2W.

Each resistor requires a laborious burn-in process and it is no different in this case.

The first hours are my full fascination with the sound! It is somewhat reminiscent of the best 2W tantalum resistors. We have a thick sound, full of proper weighting. It looks like it’s an absolutely perfect resistor. We have an amazing detail completely unheard of with such a mass of sound. In addition, we have a stretched, clean treble and very deep bass.

Then it is worse because we experience what with Z-foil resistors in the burn-in process, i.e. the sound becomes too sharp and flashy. It doesn’t reach the size of Z-foil, but it can be painful.

After about 30 hours, everything stabilizes. What do we get in the end?

The sound is ideally even from the top to the bottom of the band.

The tone is brilliant but not the golden and sweet richness of tone that tantalum resistors have.

There is no specific thickening of the middle bass. The resolution is higher than that of tantalum resistors. You have to be a little careful with them. I recommend gradual changes and trials and mixing of AN Niobium with other types of resistors. Replacing all of them with AN NIOBIUM can be too painful for the ears.

Is it the best audio resistor in the world? Maybe....