Pass XA 25 or Bryston 3B3?

They have two different design goals and therefore end up sounding different from each other. If you know what type of sound you want, then it'd be easier to make a choice. Otherwise you'll need to listen to them or at least figure out what your preferences are.

What amp are you using now, and what are you looking to improve.  What aspects of sound and system performance are most important to you?

Upgrading from an Adcom  555.

The Adcom is the weak link in the system, results in some unnatural brightness and hardness to the sound.  Also less dimensional.

Temporarily using a Krell from my other system largely cured those problems. However I want to avoid another 150 pound heat generating (12 amps continuous draw for the Krell) monstrosity in this smaller listening environment.

Also want to limit cost to less than $4K and no tubes.

Thanks again.

12A continuous?? Wow.

I am a big fan of Nelson Pass, but his Class A amps put out LESS as the speaker impedance drops. Check the specs on your speakers and see if the impedance drops, especially in the low frequency region. Any drops below 6 ohms or so will work against the Pass amp. Too Bad!  You might check out the Strake Sound AD4.320. A great amp (check Google for a review by "Home Theater something or other") and it's on sale at 40% off for Black Friday. I just ordered one. Over 200 wpc available for Stereo into 2 ohms!

I am a big fan of Nelson Pass, but his Class A amps put out LESS as the speaker impedance drops.

That’s silly, and it’s the antithesis of a Class A amplifier design.  Anyway, although the Pass may not be the space heater the Krell is it’s still gonna generate a good bit of heat so not sure how much you’re really saving going that route.   But I’m sure it’d sound great with the Pulsars and probably would be more to your liking than the Bryston given your tastes and familiarity with the Krell.. 

What I’d consider doing with your budget is buying a used McCormack DNA 0.5 amp and send it to SMcAudio to have Steve give it the full upgrade treatment.  I think it would make the Pulsars sing and put out a lot less heat than the Pass.  Just another option to consider and best of luck in your search.  Love the Pulsars BTW.  

@boomerbillione As pointed out above, your statement about Pass Labs amplifiers is simply not true. Not only does the xa25 double output power from 8 to 4 ohms, but so does *every other amp they make*.

There are a few First Watt products that put out less power into lower impedances (http://www.firstwatt.com/prod.html) but obviously those are built for special cases where the end user does not need high power and has carefully considered the speaker/amplifier match.

The Pulsars have been measured at 83dB sensitivity. See Stereophile review. I am interested in the Pass XA-25 as am amp to drive my Tannoy Sterlings.  I am currently using a BEL 1001 MK5 (50wpc). Almost purchased a used pair of Pulsars for my 12.5 x 14.5' room however did not due to the low sensitivity. Pulsars are an easy load impedance wise however. I think of them needing watts more than current. 

The Adcom is the weak link in the system, results in some unnatural brightness and hardness to the sound. Also less dimensional.

@bobbydd I think both the Bryston 3B3 and Pass XA25 will help with that, with the Pass maybe being too much of a change.

That being said, I agree with the other posters that having only 25W/ch versus 200W/ch is a big difference and would lean me towards the Bryston unless you are absolutely sure 25W/ch is sufficient headroom.

Have you asked Joseph Audio which they think would work better? 

For what it's worth, I owned an Adcom 555 decades ago and have a 4B3 now. You will hear and appreciate the difference, the "cubed" series being some of Bryston's most mellow amps -- softer sounding than my beloved 14BSST of years ago, but detailed and spacious for sure. I auditioned a non-class-A Pass amp before choosing the Bryston. I liked the Pass a lot, but the heat was unbearable in my room. The latest Brystons run quite cool and have great sound.

I didn't think the Pass was better than the Bryston or vice-versa. To my ears, the Bryston is more neutral, in a good way; the Pass, a little romantic, in a lovely way.