does Leviathan == EC 2A3x4 now?
Not remotely. The price and performance difference will be substantial with few if any peers. I certainly haven't heard a single headphone amp that is comparable otherwise I wouldn't be doing this.
I have heard a potential transformer replacement for the Tangos and impressions were very positive. I feel 95% confident we will now be able to move forward over the next few months and complete the project and meet or exceed the performance of the original prototype.
Hang in there folks.