[AllanS]

The Nelson Pass interviews on Youtube with Steve Guttenberg are a good introduction to the First Watt and Pass Labs amps and the design approach. The Nelson Pass presentations at Burning Amp are also interesting..

 Even with quiet listening, I get imaging and texture in the deep bass and subtle details down in the mix are audible.

Thanks much for the pointers and the details of your experience.  The short list isn’t getting any shorter but the XA25 sure is solidifying a spot high on the list.

Edit:  I neglected to add that manufacturers who offer a lot of information on their websites get high marks.  I take their offerings as evidence of the care they have have for what they do and respect for those who want to know.  Pass Labs Technical Articles are a great example https://www.passlabs.com/technical-articles/

[RDavidson]

So maybe the only thing that's obvious is my ignorance of the Pass Labs line up.  I haven't yet but will look at the First Watt line up to get better idea of where and how the XA25 fits.  Thank you. 
But since you mentioned it I would appreciate understanding your listening preferences and other components and how the XA25 is a better fit than XA30.n. 
I'm really most interested in relatively low SPL performance than anything.  I'll crank it up occasionally but 99% of my listening, even critical, is going to be < ~65-70 dB average at 8' from the speakers.
Thanks again.  This is all very helpful.

I also listen nearfield and at rather modest SPL's like you. The XA25 is a special amp. It is neutral, detailed, and refined while also sounding wholly natural and realistic. Bass tone and control is wonderful even at low volume. I've owned many amps that just don't do this. You have to goose them to get them to perform their best. The XA25 just does everything so well and in such an even handed nature, moreso than any other amp I have ever owned. Sure some other amps have characteristics that some may prefer (including others in the Pass and First Watt lines) but the XA25 is truly an easy recommendation. Newzooreview summed it up very well earlier. For your preferences, I think you'd be very very happy.

[AllanS]

I also listen nearfield and at rather modest SPL's like you.
Newzooreview summed it up very well earlier. For your preferences, I think you'd be very very happy.

Many thanks.  I appreciate your help.

[Chazz5]

If the XA.25 is an entry-level product from Nelson Pass, I guess so is the First Watt F8, which I use at mid or lower volume. It is a delight to listen to. I hear no coloration, I don't feel I'm missing anything in the music, and I can't find anything in the sound that I wish were more or less.
 
A Van Alstine Transcendence RB 10 preamp feeds the F8, so it shares the credit. The speakers are Focal Aria 906, rated 89.5 dB sensitivity.

[AllanS]

Does anyone find that the XA25 runs hot, say too hot to lay your hand on?  I ask only because my system spends most of its 10 hours a day 5 days a week relegated to background music, which is way low SPL say in the 30s.
Thanks.

[aniwolfe]

Does anyone find that the XA25 runs hot, say too hot to lay your hand on?  I ask only because my system spends most of its 10 hours a day 5 days a week relegated to background music, which is way low SPL say in the 30s.
Thanks.

No, it does not run hot and I can lay my hand on it without bother...it's more like Med Warm to me.

[jjss49]

in my use, it does run hot... quite hot - you can put your hand on the heat sinks but you can't hold it there for more than 6-7-8 seconds before it gets quite uncomfortable

[newzooreview]

Does anyone find that the XA25 runs hot, say too hot to lay your hand on?  I ask only because my system spends most of its 10 hours a day 5 days a week relegated to background music, which is way low SPL say in the 30s.
Thanks.

No. I have had the XA25 running for 12-48 hours at a time as I break it in, and I can walk up and put my hand on it at any time. With a FLIR temperature sensor, the fins will stay in the 48-51 C° range (and most often below 50), which is very healthy for the amp.

The manual states "Leave a minimum of 6” of space around the amplifier." I can only give it ~1" on the sides, but I have about 10" of clearance on the top, and this seems to work just fine. It is on the lowest shelf, so it's in a good spot for natural convection to waft cooler air from the floor upwards to vent the XA25.

When I first got it, I only had about 4" of clearance above the amp, and after a few hours, especially with bass-heavy music, it would get up to 56-58 C° or so on the fins at the top. A bit too hot to hold my hand on there for a while. Once I gave it more breathing room on the top this was not a problem.

I did call Pass Labs to get some clarity on things. They said that they bias the amp so that it is running at 50 C° (assuming the room is in the 20-25 °C range, so approximately +25 C° over ambient temperature.) They said they do this because as it gets above 50 C° the amp quickly starts to feel too hot to hold your hand. They also said not to worry too much about it since the automatic shutoff will prevent the amp from damage due to overheating.

So, again, in my experience it can very easily run 10 hours a day with adequate ventilation, even at 70-80 decibel listening levels and certainly at lower volume. If your speakers are easier to drive than the 3.8 Ohms of the Sapphires in the bass region, and if you can give it the full 6" of breathing room on the sides, then things are even better.

[RDavidson]

I run my XA25 all day, ~10 hours a day, 5 days a week, at low levels while I work. It never gets too hot to put my hand on. I have it sitting on an amp stand (maple block) in free space. I take it out of service in the summer because my office space is not climate controlled and the additional heat from the amp can contribute to raising the room temp slightly. For comparison, it doesn't get nearly as hot as the XA30.8, which isn't a big surprise because the 30.8 is a bigger amp and biased deeper into class A.

Something to note : Pass Labs has absolutely top notch customer service. If you have any questions, give them a call. And the beauty of owning great gear, built here in U.S., is if anything goes wrong you send it within the continent where it was carefully built by hand to begin with...vs to a random technician or service center or possibly even overseas. I'm assuming you're in the U.S. though Pass does have international distributors. I've read stories of Pass Labs fixing things free of charge despite being outside the warranty. I think they're able to do this because they have quite a track record of vanishingly low failures in the field to begin with. Most of the time, things that need fixing are simply age related...like replacing old capacitors after ~20 years.

[AllanS]

Three out of four not running hot are odds I’ll take.  Many thanks.

If your speakers are easier to drive than the 3.8 Ohms of the Sapphires in the bass region, and if you can give it the full 6" of breathing room on the sides, then things are even better.

I won’t know until I spend time with them but I expect I’ll order the M4 soon.  I’ll have plenty of clear space for cooling.

Pass Labs has absolutely top notch customer service. If you have any questions, give them a call. And the beauty of owning great gear, built here in U.S., is if anything goes wrong you send it within the continent where it was carefully built by hand to begin with...I'm assuming you're in the U.S.

This is encouraging.  Seems as though nothing is built to last anymore.  I am in the States but on the opposite coast.   Actually I used to call Sacramento home, not far from Pass Labs.

[abomwell]

An XA25 was just listed at The Music Room if anyone is interested.

Al