I'm not sure how many people did that. . . I did.

It was a SIGNIFICANT upgrade. First off: the ZTPRE has ZERO noise. I had one CSP2+ a it quieter than another, neither was terribly noisy, but I could get neither ruler flat quiet. The ZTPRE has a circuit Steve says prevents hum. It does.

Due to this alone there is thus a subtler sense of tone and dynamics. A bit more body to the image and weight to the presentation, and especially micro-dynamics are slightly more easily perceived.

And there is more potential gain available with the ZTPRE compared to the CSP2+ which may or may not be a concern. I find that my Taboo craves more gain from the ZTPRE than the Torii does. It's very nice to have and allows compatibility with a lot of amplifiers. On top of that the remote control option is very nice--don't need to explain that, but it's also nice that there are dual potentiometers allowing one to adjust incoming gain for each channel.

It's an odd thing. The ZTPRE seems both more powerful and influential than the CSP2+ AND it seems more "invisible" than the CSP2+ by not really having as strong a character of its own to impart and by being freed by the balanced nature from certain noise potential. I forget about it. Twice I've taken it out of the system and yes I still have really good sound, but something seems missing until I put it back in.

Hope this has been helpful.