Part 2.
I bought a Rogue Cronus, later upgraded to Magnum. The coupling cap in the former were cheap Mcaps. In the latter Mcap Supremes (IIRC) that are better. The latter were also bypassed with polypropylene caps. After listening for a good while I removed the bypass caps and found the sound more coherent and just as extended in the treble. Previously the treble was a little bit ahead (time-wise) of the mid-range. Unfortunately there is no room in the amp to upgrade the coupling caps to anything better.
I also bought a Havana DAC and changed the output coupling caps to Jupiter HTs. These made a big difference from the stock proprietary caps in resolution, transparency, bass response, tonal accuracy and harmonic richness. In that form both I and a friend thought it was clearly better than the stock Eastern Electric Minimax DAC.
However after said friend modded his EE, it surpassed the Havana so I bought one and had him do the same mods, including changing the output coupling caps to Auricaps. This produced a sound that was more resolving, very neutral, and very well balanced.
Again, given my speakers I wanted more richness, so I asked Scott Gramlich to change the Auricaps out for Jupiter HTs. The latter are huge (as all first class caps are) and required running the wires out of the chassis to a project box velcroed to the top of the unit. The difference is tremendous. All of the virtues listed above are apparent along with a much greater soundstage depth, more prominent inner lines and more clarity to the layers of images.
The two things that stand out the most for me with these caps, however, is their tonal accuracy and even frequency balance. Unfortunately, I can't afford Duelands but I'm extremely pleased with the HTs.