I've a Calypso, no experience of the Coincident and I've not heard the Sig.
The Calypso is a fine pre, the one thing to be aware of is the unit drives tubes hard and noise can be a problem with very sensitive speakers. You also need to budget for quality NOS tubes to get the best from it.
I was at a dealer today, I'd heard his Reimyo/Soulution/Verity combo briefly a month or two a ago and was blown away. He's made some changes since as have I.
The experience was not the same this time around, as I listen to my system now I'm pretty happy, sure on some stuff that Soulution system offered up greater transparency. I would guess there is greater potential but my system plays some of the music I enjoy in a way I prefer to that system. A big surprise.
The Calypso is at the heart of mine. Whether it'd work in your system and room only you can judge. The Calypso does have the potential to recreate wonderful music at a pretty modest cost.
I've investigated opinion on the Signature, there does seem to be a consensus that it is a step up in transparency and portrays music in a natural and very neutral way.
