Which preamp for VAC Phi 170 IQ?

Really depends on what sound characteristics you’re looking for. 

Still on the process of upgrading my amps and later the preamp.
I’m considering a pair of VAC phi 170 IQ configured as monoblocks, currently using von schweikert endeavor se. May I have some feedback on phi 170?
Thanks.

The AVM is excellent for the money.  It allows you to fine tune your output for a perfect match with the VAC.  AVM is one of the easier preamps to match with other brands for that reason.  

Buy a used Aesthetix Calypso or Calypso Signature. You can upgrade to a VAC later if you like and sell the Aesthetix for about the same price as your purchase price. Balanced and SE in and out, with an excellent volume control.

I've used a Rogue Athena with 200iQ monos and enjoyed it about as much as with Renaissance V. Balanced ins & outs, nice tube complement of 6H30. Doesn't sound too tubey or too solid-state. Unfortunately it's discontinued (and their newer preamps were not as good a match with these amps), but when they pop up used, they run low to mid 2000s. The Hera I is even better but unfortunately most of them are Hera II's where Rogue raised the gain to very high, noise & microphony inducing levels.

If your main source is vinyl though, the phono board option of the Ren V is hard to beat without spending much more. I love VAC phono stages.

Zesto makes amazing gear that challenges the vac gear yet is way less expensive 

The zesto gear is balanced as well

Dave and troy
Audio intellect nj
Zesto dealers