I bought the C-1's for the second time.
In the interim after selling the first pair, i took a journey with Merlin, Reference 3a, Dynaudio Special 25's, Harbeth, Magnepan's and Quad ESL.
The last 3 were excellent, but lacked that something special the C-1's offer.
This time I went all tube with Lamm LL2, LP2 and Manley 250s all retubed with NOS tubes and the result is warmth, bloom, coherence, perhaps one of the best mid range presentations. I am using Purist cables as well. This speaker needs power and some people say it needs SS electronics, but I disagree, especially if you appreciate the warmth. The Manley's are warm
with el 34 tubes and with 250 watts per channel have an iron grip as well.
I think the trick is voicing the system with enough warmth to satisfy your taste, but retain resolution. If you are looking for resolution the Nordost suggestion is excellent as is going with Audio Research electronics, but the key is experimentation to create the balance. I tried a Koetsu cartridge which didn't work well, so I went to a Dynavector XV1-s which is incredible in the system.
I was able to buy everything on audiogon at nearly 50% off, so the cost although expensive was achievable.
I hope this helps.