I had a VTL ST-150 and a transformer volume control preamp. Source was a Nott Spacedeck/Benz Micro L2 at the time, and a Tube Research Labs modified sony cd spinner.
No experience with the Nu Vista amp.
My thoughts on the Sophia were that they imaged very well and were very dynamic. However, the midrange was smooth and lacking in detail, not very expressive at all. I had three speakers in house at the time, the Wilsons, Piega P-10s and Green Mountain Audio C3 HDs. I kept the C3s and sold the others.