Swapping W4S to Pass Labs XA- worth it?

It is my understanding that the 30 watt rating is the maximum power provided while remaining in pure class A. This Pass amplifier is capable of somewhere in the range of 150 watts class A/B into a 4 ohm load. 
Charles 

According to Stereophile measurements it goes to 195 watt before clipping into 4 Ohms, It is still less then 450 into 4 ohms by Wyred4Sound (or 350 by my old Krell), but still should be plenty, Or so I think.

The only measurement concern I have is iinput impedance (30K for Pass vs 100K for W4S), as I will drive ( driving) them directly from CD player/DAC.
But more importantly - will there be serious difference in sound quality. Did anyone ever compared them both?
I do not have "golden ears", but for example when I swap various CD players/DACs I can hear often significant differences. With amps I simply do not have enough experience.

It's a no brainer.

If they can drive your speakers, I would go with the Class A Pass Labs. I think the 0.8 series have higher input impedances.

Just checked - output impedance of my CD player/preamp is 300 Ohm, so in theory 30K input results in 100 ratio, which should be OK, I hope. 
Wonder if anyone drove Triton One with XA30.5 (30.8)?

I've successfully used an XA30.5 with 85db speakers.

I'd have trouble thinking of any Pass and any W4S product even remotely in the same league.

Tell us what the Pass would have to do that your current amp doesn't do that to you would make it worth the change?  I imagine they will sound slightly different, but without knowing you goals, or even the rest of your system, it's hard for anyone to say whether changing will be a good decision.

It really appears strange that you seem to want to run the Pass amp in A/B mode.

Stereophile measurements of 30.5 shows quite different numbers then 1% at 30 watts, in fact extremely different. I think 1% is at clipping when in AB. Here are those charts. https://www.stereophile.com/images/archivesart/509Pasfig4.jpg

I am not "planning to run it in AB mode", I just want to ake sure it does not clip in HT mode. I never listen to stereo at very loud volume.
As far a goal - I may be like more "liquid" presentation of some music, which in my case is small ensemble modern classical music, opera, small jazz ensembles and jazz vocals, and classic progressive rock.

For stereo listening I am planning directly feeding amp from AYON CD-5.

Well, I decided to pull a trigger on used 30.5 (late build, less then 2 years old). 30.8 is simply too big for my rack and will stick out too far. Will report results when all received and set up )))

PS I am not using preamp, instead I am switching amp inputs via Rolls SS32 switch, a very well build simple device

Hello Michealkuz, 
Congratulations on getting this amplifier and I believe that you'll be very happy with your decision.  Given your (stereo) listening volume habits and music genre  I doubt  you'll use more than a few watts (the majority of your listeniing) and will rarely move out of class A operation. Let us know your listening impressions. 
Charles

OK, as I promised - reporting on Pass XA30.5.
Listened to it for more then 2 weeks now
It is definitely better, then W4S. The difference is not "night and day", definitely not like AYON CD-5 vs OPPO-105. That was night and day, with Ayon blowing me really out of the water. This is more like "night and dusk" so to speak.
I am not reviewer and cannot describe all in audiophile terminology, but sound is more "natural" for my ears, and more detailed at the same time. Especially on small classical quartets, music I heard live very often - cello is spot on, which I never was able to achieve in my system for years.
Imaging is actually very close call - may be W4S ST500 II amp is pretty good indeed, as some other people say. It is just not Pass Labs.
With my GoldenEar Triton 1 needle on a meter almost never moves. I have to crank sound to level I feel uncomfortable to see it start to move slightly.
Two additional observations -
1. I can hear more details with lower volume then before, surprise.
2. In HT settings (I recalibrated system due to different amp gains, I use Anthem 720MX as a processor) and for 5.1 recording sound improved quite a bit, more then I expected. the whole presentation became way more organic, and I gave my collection of awesome Steve Wilson classical prog remixes a new spin. Dunno if it is amp or recalibration or both.

At the end I would like to thank everyone who participated in this thread and pushed me into decision to switch amps - money well spent.