...do great speakers increase in value over time in the vintage market?

using 14g solid core copper wire twisted, with bare ends, as speaker wire (may experiment with lampcord at your suggestion... )

Uh, that was not my suggestion. That was simply what we used, because back in the 70's everyone I knew was under the spell of Stereo Review and Julian Hirsch saying the wire just needs to be thick enough gauge. Many years later I learned just how much better wire can be. But back then it was lamp cord. Ordinary wire. 

Wonder how not being mirror-image affects sound dispersion.

Well its asymmetrical that's for sure! But that's the least of it. The baffles are wide, and the baffle is even recessed into the cabinet. About the only thing they did right was the little ring of foam around the tweeter. Better than nothing I guess. But hey, this was the 70's! 

At least you got the more tasteful cream color. Can't be sure after all these years but it seemed I got a deal partly because nobody wanted yellow and orange!

Actually no, that has nothing to do with his question. The degree to which you have misconstrued it is however hilariously impressive.

What color are these bad boys anyway? Mine were yellow with orange grills. They came in 4 or 5 colors. I was watching and got mine when they were marked way down. Plus mine were store demo. I said hey what about this nick on the grill? Bottom corner, barely visible, but good for another $25 off. Well you have to be careful with your paper route money, you know?

We're talking Kenwood KA-something or other 60 watt integrated, Technics SL-1700 with Stanton 681EEE, lamp cord and patch cords. Nothing back then even had detachable power cords so you can imagine. I was however dedicated enough to tin the ends of the lamp cord.  

I would go with a turntable and the smoothest amp I could find, turn the tweeter down a bit and enjoy.

Your "bandwidth" and ability to relay that pleasantly continues to awe me ( and I did correctly mean awe, not augh!...)

Thanks for your blurb here...

You're welcome.

BTW: in another forum - if I remember correctly - you said you had these once upon a time: any comments about them?

Yes the L25 Prima was my first real speaker. Well, the I can remember. I forget the Radio Shack ones they replaced. The L25 won out over the Advent as it was much more lifelike (I was in band at the time and hearing live instruments every day) and a lot more efficient. Really wanted the L36 three-way with its nice wood cabinet and midrange but my roommate had a pair so heard a lot of both, the L25 was close and both were better than anything similar in price back then and for many years.

When I built my first DIY speakers, the Roger Sanders transmission line, it was using the 10" woofers from the L25. Their bass response in the TL was impressive. But they were impracticably large for that stage of my life and the woofers went back into the L25s. There they stayed until around 1989 the surrounds began disintegrating.

At this point I made a real blunder. From 1974 to 1989 these JBLs were my reference. In 1974 my reference was real live musical instruments. Trumpet, French horn, sax. By 1989 my reference was L25. Know it now, didn't know it then. Consequently in my mind when I went shopping was that JBL sound. Looking back, I passed on a lot of very good speakers because instead of appreciating what I was hearing I was trying always to match it to my old speakers. The blunder was not realizing this is what was going on. Oh well. Know it now. Live and learn.

As long as you have them, enjoy them. They have endured long enough now to be at least holding their value. But realistically, only to those with an interest in their 70's mod style looks. Or still nostalgic for that JBL sound. I could see a really cool period system with those. If you ever sell, I hope you will take the time to wait for the right buyer. They have endured a long time. Would be cool to see them around a lot more years to come.

Matter of fact everything does this. Just try and find something from 1972, still around and in good condition, that’s not seizing for more now than then.

General rule is 15 years of depreciation is followed by endless appreciation. Yes folks another one missed by everyone but me.