I haven't heard the ACT 2. I had a Premier 17LS2 for a short time (about a month). The ACT 2 is better than it, I believe.
I was happy with the 17LS2. I had upgraded from a PV-14L. But, the 17LS2 had an issue (static), so after trying numerous different tubes, I returned it.
A forum member from the c-j forum on Facebook recommended the Linear Tube Audio MicroZotl preamp with level 2 upgrades. I bought one. I much prefer the LTA to the c-j.