Grannyring, the midrange texture and presence is undisputedly"The Best".
Strange that you found it tipped up, as i clearly confirmed testing in separate setups, it is midrange centric and tipped up in the upper mids. I found the cast resistors caused the uppermids to be tipped up.
The Jupiter coppers are very nicely balanced overall, but i don't exactly find the "special" in any way.
I have be trying to bypassing the 1uf cu duelund and have found a 0.1 mundorf SIO to be nice overall - more highs, details, faster with better bass. The 0.01 vcap tftf has extremely deep bass and clear but causes the midrange to go flat!
I will be trying a SGO bypass, on order as the duelund 0.01 silver foil bypass are out of stock of another several weeks. I wonder if this will be the best way to extract and balance the sound of the Cast Cu.
I happened to come accross last night a dutch (i think) reveiw of the new hubrid Duelund. It,s basically half a CU cap connected with another half(at least they say) to form 1 cap of the desired value. Orientation of silver +ve and cu -ve is recommended.
It was still found to be lacking in the exact same areas discussed above in my findings, but improved upon the CU. It still did not bring out sufficient speed, highs, deep bass. The review found the opposite orientation with silver portion out to be slighter better, giving more of the silver tone.
I think if it works, a bypass with a small silverfoil cap might be the answer. Sadly, to retain much of the Cu's tone and bring out the highs will inevitably cause the loss in the tone and analogue smoothness of the CU cast. Any cap which opens up the staging and frequency extremes will disturb this delicate balance. Especially a pure silver foil bypass, any comments?
The review ended that all duelund was not the way and he has a jensen pure silverfoil to replace the 2nd set of CU cast in his preamp stage and found it to be the best combination.
The Duelund or full Duelund will still be best for certain types of music, i.e vocals, chamber and classical.
So i may end the quest for the perfect cap and live with a small bypass. Sadly, didnt couldnt get myhands on the new duelund silverfoils to test.