@fastfreight I'm running a vintage Krell KSA 300S with a Krell KRC-2 preamp with my C 60's. These speakers are quite difficult to drive (EPDR of 1.9 ohms) but they are not as difficult as the 30's which have an EPDR of 1 ohm. I'm fortunate to have an amp that can drive anything (the KSA 300S puts out 300 watts at 8 ohms and 2400 watts at 1 ohm) so I didn't have to worry abou that aspect of the speaker's performance. The C 60's also have low sensitivity which puts a huge demand on the amplifier. I can drive my Krell into the highest bias level before the Dynaudios show strain (around 110 db) and I listen at high volumes (around 100db) fairly often. I would not want any less power or current. One downside is that when playing at high volume my amp draws about 1500 watts and gets hot enough to fry an egg.
I'm seriously considering replacing my amp and preamp but to get equal performance will cost at least $60,000 for the pair. If I went with monoblocks the cost would exceed $100k. The kicker is that I'm not sure I would get significanlty better sound. New gear would be quieter but I have never felt that noise was an issue in my system. For me it's just not feasible to try to borrow $60K worth of amp and preamp, bring it home from 200 miles away, compare it for a week, and return it - assuming the dealer would even allow this. In my opinion, evaluating an amp/preamp in a dealer showroom or an audio show is an exercise in futility.
I'm going to the Southwest Audio Fest in Dallas in a couple weeks and I'm looking forward to listening to some high end systems so I can better calibrate my expectations. After careful setup and break-in I'm in awe about how good my system sounds. I don't know how it gets much better than this.
I haven't heard Vivid speakers but maybe they will be at Dallas. I decided to narrow down my choices to speakers that I could audition within a long day's drive and I don't believe Vivid has any dealers in my area (I live in central Washington State). I was especially interested in auditioning speakers from Rosso Fiorentino, particularly the Sienna 2, but there are no dealers in the western US. I heard a different model at AXPONA in 2018 and I really liked it but I can't bring myself to buy a $50k pair of speakers without hearing them.
One last note while I'm at the keyboard. Speakers like the Confidence series or my previous speakers- Thiel CS6, come with what I call an "amplifier tax." They have impedances that dip to low levels and will not perform to their potential with amplifiers that cannot increase their power into low ohm ratings. If you drive them with something like a tube amplifier or a SS amp with output transistors, they will make music and may even sound OK but you are introducing a tone control that the speaker wasn't designed for. I was active on the Thiel forums and I saw several examples of people running their speakers with low-current amps and complaining about the sound. Duh. You can bet that the engineers who voiced the Confidence series weren't running a low-current amp. This is one my pet peeves so thanks for letting me indulge myself on this issue.