I have a Calypso. Purchased with mullard tubes from Kevin Deal at Upscale Audio. Have not done any tube rolling but will report on it when I do. I have about 150 hours on it right now. It is a fabulous sounding pre. Like clear water. Break-in made a huge difference. Started out with a lot of sibilence on female vocals, but mellowed out to perfection around 80-100 hours of use. Using it with AES Sixpac EL34 monoblocks.