freesole,
I'm just offering insight on the JA Perspectives mostly because it's hard to find people with much experience listening to them aside from hearing them at shows. And since you (and others) have heard the Magicos, I don't think giving my own long impression here would be add much.
I don't own the Perspectives. I was taken by them when I auditioned them over a year ago and wondered if they might replace my big Thiel 3.7 speakers, so I had a couple day home audition. They blew me away, but so did my Thiels. I decided I couldn't give up the Thiels and instead I'd just add the Perspectives to my "collection." Saved up for a long time for the Perspectives. Once I just about had enough I figured I'd survey the speaker landscape of other choices to make sure I'd be making the right choice on the Perspectives. Hence my long speaker audition thread.
But that also had me re-auditioning the Perspectives again to compare with all those other speakers. So I have a lot of "audition time" with them. (I don't own them simply because a financial requirement arose suddenly that made my purchase impossible for the time being).
Anyway....
As for lower powered tube amps, I've heard them sound excellent on 100W tubed Mcintosh amps. People raved about the Perspectives in a recent show, powered by the Doshi tube amps, 65W.
I never got around to testing them on my older Eico HF81 tube integrated (14 side), only on my CJ tube amps, 140W.
As for warmth in the sound: the JA speakers have a "warmth" in the mids/lower mids/upper bass but it's not necessarily in the sense of "big, round, lush." It's not that kind of emphasized lower mids warmth, or the Big Fat Midrange sound you get with many wider-baffle speakers like Harbeth, or especially Devore "O" series speakers. The Devore speakers, for example, give the midrange Big Fat Weighty sound.
The JA speakers sound more linear, and do have something of that "narrow profile speaker" sound, so bigger speakers will present a sax that sounds bigger. But they nonetheless have a richness right were it needs to be in the warmth area, and a particularly "human timbre" richness where male voices have that richness you want, and female voices sound particularly superb.
The main difference in character I think you'll find in essentially neutral speakers like the Magico, Spendor and Joseph are, to my ears, that smoothness inherent in the Joseph speakers, the lack of grain. This allows them to have extended highs, crisp transients, like you might expect (to use cliche) from metal drivers (even though they use a soft dome tweeter). Cymbals sound really "metallic" and with great individual character, rather than bursts of white noise. But the lack of grain to the sound makes it unfatiguing to listen. (In fact, the lack of grain/hash can sometimes lead the JA speakers to sort of sound a bit "darker" than some other speakers, even though they are pretty linear and extended through the high frequencies. Though they can of course sound too bright in the wrong situation too). It's a subtle difference, but if it grabs you, it grabs you, and it's why I preferred the JA speakers even over the Magicos.
When I listened to the Magico speakers, I heard tons of detail and sonic information, that really made instruments sound individual and holographically rendered. But they just didn't do for me what I get as soon as I play anything through the JA speakers. There's almost a hair-raising-on-the-arms sensation of "wow, that is what a piano, a voice etc" actually sounds like! It's not so much "sonic detail that allows me to differentiate everything" in a sort of intellectual way, but more like the fact that different materials, metal cymbals, horns, wood instruments, steel strings, gut strings actually SOUND like they are made of those materials, and less like a homogenized timbre.
I'm a bit of a tonal/timbre nut, so that's why the JA speakers really grab me.
But...we all tend to focus on different things, and in that way "hear" differently when we are shopping for speakers. So you could feel different than I do in comparing the three brands. (Though, I would say, that my own impressions of the JA sound line up with what seems like a constant theme from users and show reports - usually the remarks center on their timbral precision, soundstaging, and dynamics).
Though, again, even though the Perspectives punch well above their small size, I would think if you want an even more authoritative sound, in terms of frequency extension and presentation, the Magicos would likely do that more. (And maybe the Spendor 9s, though I haven't heard them in a while).
