Pass Labs int 60 vs. Luxman 590 uX ii

Thanks, Erik, I appreciate it. I assume the flip side of that is that some amps do well, i.e. double their power when the impedance is halved, others fall short. I don’t begin to understand enough about amplifier design to know the whys and why nots, wish I did.

George, I read your stuff with interest as well. That being said, not really sure why you’d be throwing the ’fanboy’ slur around. I’d be very interested in listening to Pass Labs. The chance hasn’t presented itself, though. I’m very happy with my Luxman, if your opinion is different, I’m okay with that.

I do like both, but Pass is beter in low. Both are detailfull and very open , 3D
I had the Luxman and was a little bit to “sharp” , Less detail in the lower area. Pass have a good combination between High-mid-low. I prefer Pass.

Builer,

It's a little more subtle than that.  Most amps will double in power as impedance is halved.... down to a point. 

From 32 to 16 to 8 to 4.  That's Fairly typical for most amps to handle.  As the speaker impedance gets close to the amp impedance though, this vanishes.  The power never gets to the speaker, and things sag.

It's my experience throough a lot of listening and cable comparisons, that amps _can_ be a little more sensitive to this problem, cable and speaker impedance, than we have thought.  How much it is worth to fix, whether it is bad, and what a particular amp/speaker combo will sound like is another matter.

not really sure why you’d be throwing the ’fanboy’ slur around.

I was a big fan of Nelson with Threshold (bi-polar), but not so much with complimentary push pull Mosfets Pass Labs, as the P channel Mosfet always let them down big time for current delivery, but fine for easy to drive speakers, I tend to like ones that just happen to be pigs to drive Wilson Alexia etc etc
 
But there have been a couple of Mosfet amp manufacturers lately that have used only the N channel mosfet for both the complimentary push pull pairing, and they get just as much current from those as big bi-polars like the old Thresholds gave and today Gryphons. Agostino, Krell etc etc. I’ve yet to hear any of them, would love to though.
One is the Constellation Audio power

" Instead of the usual push-pull arrangement of N-type output transistors for one half of the waveform and P-type devices for the other half (each of which has somewhat different performance characteristics), within each Centaur Mono are a pair of carefully matched "floating" (ie, not referenced to ground) amplifiers, both using only N-channel MOSFETs. (There are eight transistors on each half-bridge, for a total of 16.) One amplifier is fed the balanced signal’s negative phase, the other the positive."

And this is what it did on test, and it a Mosfet!! (but only N-Chanel push pull)
520W into 8ohm
830W into 4ohm
1210W into 2ohm

Cheers George

Larseand, what a nice problem to have. Can’t listen to the amps in your system and asking us to pick one for you based on our experiences. Looking at the responses here, it appears that most only have experience with 1 amp and that’s the only amp which is recommended.

FWIW I was offered both Pass labs Int60 and Luxman L-590AXII about 5 or 6 months ago. Similarly I can’t listen to both in my system and have to pick one. In the end I chose the Luxman and am glad to report that it matches very well with my speakers. I don’t think you will go wrong with either one although they both don’t sound alike. Since you own Focal 1038Be which is known to be a rather bright speaker, the Luxman and Pass Labs Class A will be a good if not great match since both amps sound smooth at the top. If you have a tough decision, perhaps pick the one that looks more appealing to you.