I have tried a Calypso also (two of my friends have them) and tube rolling (except the latest tubes Jim has sound great) is a requirement. Plus one of my friends had your CJ 2500A amp (with a transformer humm that CJ would fix saying they all do that...he sold it) as good as that amp is I bet the Calypso was showing you how digital you digital front end is....
What is your front end? As you start to get to these truely great preamps they also reveal all the flaws in a system instead of masking them in syrup.
Like you already found out system synergy is key, I had a huge ground humm that I couldn't cure with the Calypso in my system but it worked perfectly at my friends house or I would own it.. bargain component.
The LS16mkII is another great preamp if you need single ended only.
What is your front end? As you start to get to these truely great preamps they also reveal all the flaws in a system instead of masking them in syrup.
Like you already found out system synergy is key, I had a huge ground humm that I couldn't cure with the Calypso in my system but it worked perfectly at my friends house or I would own it.. bargain component.
The LS16mkII is another great preamp if you need single ended only.