Audio Experience Concerto tube phono preamplifier

Does anyone have any experience with this piece?

I currently have an NAD PP2 with upgraded power supply.

Would there be much of an upgrade in sound?

I can get it for $250 ... am I better off spending a bit more to get something considerably better than the NAD?

My system:

Rega Planar3, Dynavector 10X5, bryston b60, Signet 280ex (about to upgrade to Totem Arro or Sttaf)

Thanks!