Duelund cast Pio Hybrid Copper/Silver or Rs series with Silver Bypass PIO

In general, copper has never let me down. I've not gained anything by adding silver/gold to a mix when it comes to capacitors or wires.

YMMV.

Best,

E

Zipost, 
I use the Duelund CAST copper capacitors in my Coincident speakers at the tweeter crossover and as output capacitors in my Yamamoto YDA DAC with superb results. I'm thoroughly satisfied with these upgrades. 

From what I have read from those who have done actual listening comparisons the addition of silver seems to improve performance even further yet.  I personally have no direct comparison experience but I don't doubt the impressions of those who do. 
Charles 

For your use I would stick with the copper CAST. They are wonderful. I am not sure you need to add the bypass silver cap to be honest. Sometimes resolution can be taken too far and long term listenability can suffer. Many recordings are less than perfect 😁

I agree with EriK on the copper Duelund CAST and even the RS as my go to choice. Also, sometimes adding a bypass cap in high voltage electronic applications gives a strange sort of result. Sometimes it can be good and sometimes not as good. Crap shoot and with this kind of money I would not take the risk. Stick with one high quality cap and you may well be better off.

Lastly, don’t discount the Jupiter copper foil cap. I actually like it every bit as much as Duelund copper CAST and they cost far less. Sonic Craft has great prices on these wonderful caps. The Humble Audio site rates the Duelund caps a little higher, but remember these were only tested in low voltage crossover networks, not electronics for coupling. I have compared both in coupling positions and the Jupiter copper foil caps were wonderful. The CAST copper were also wonderful. The Duelund is quieter with a dead silent background. They also had a very slight emphasis in the upper midrange. The Jupiter caps had more air, improved Micro details, and were more even handed through the upper mids. 

Food for thought!