Thanks for the nice review. It a good example of a review where the comments and measurements clearly tell the reader that this speaker is worth hearing. I'm reminded of a recent thread about Zu Audio speakers, where their poor-looking frequency response curves was a subject of debate. It suggested to me (and others) that those speakers had significant flaws and might not be worth an audition. In contrast, the PSB graphs look very good.
I especially liked seeing the frequency response graph comparing the sound with and without the grills. It does show small differences only in the higher frequencies, a 2.5 dB dip around 4 to 4.5 kHz and a broader 2-3 dB elevation from about 8 to 15 kHz. In my opinion, these variations at the higher frequencies, might be less audible or objectionable sounding than the roughly 5 dB dip in the main FR curve located in the more audible range from about 500 to 1500 Hz.
I'm not concerned about the use of what appears to be electrolytic capacitors in the crossover. The FR curves look good. In my limited experience as a DIY speaker builder, the worst problem about electrolytic caps is that many of them are out of spec when they're new. To find one that actually has the capacitance printed on its label, you might have to buy 10. Poly caps almost always deliver what they promise. But if PSB can get the job done with less expensive caps, good for them. I disagree with claims about audible differences, between electrolytic caps and poly caps in crossovers. And, yes, I've been part of a blind listening test of some 40 or 50 listeners, where this was examined.
At 2k$ a pair these PSB speakers look like competition for the Salk SongTower. I wonder how they sound in comparison. Has Tom Andry heard them?