Where to go in Portland...

It's been a few years since I was last there but I can highly recommend Stereotypes Audio, https://stereotypesaudio.com/. They have one of the largest, most interesting lineups of high-quality gear I've ever seen. I walked in on a demo of big Harbeth speakers driven by Simaudio separates and was astonished by what I was hearing. It was one of the reasons I began buying Simaudio gear.

Echo Audio. They sell both new and used gear. The owner Kurt is one of the most ethical people I've met. He's talked me down from buying something that wouldn't improve my system more than once. 

Two great suggestions— Thank you!  I knew this was the right place to ask!

And I agree with big_greg. I didn't remember the name of Echo Audio but I also had a very good experience there.