What are the weak points of Pass amps and pre-amps ?

THE meter is useless and you're paying for it anyway. The speaker "wing" connectors on Pass and many other top brands can make it difficult to connect heavy speaker wire with spade lugs. If you don't get the XS series with outboard power supplies you're not getting everything the company has been able to achieve. Any preamp or integrated amp without at least ONE tape loop (IOW a fixed-level output jack) is off my list of versatility. Also one must consider whether or not you can listen to headphones or not, even with an external headphone amp. As for X or XA, it's certainly a conundrum that makes you choose one or the other, and if you're not happy after 3 months or ? months with the sound, you're going to give yourself an "ulcer" thinking you made the wrong choice, making the hobby even MORE complicated than it is already.
My dad had a Blaupunkt TUBE radio many years ago that sounded so sweet and smooth
in spite of its limited power, etc. that a lot of people here may not have ever experienced. So it pays to understand just what solid-state is up against if you want to evaluate what's possible. Having said all that, Pass is a good fit for most audio "fanatics" and should satisfy most of us that can afford something they make. Not all speakers are a good fit for a Pass amp , but that would not be an excessively long list. My main beef with ANY product is limited connectivity, whether it's a reel-to-reel or wire, headphones, a subwoofer, whatever you need it to do.
Lastly, some components looked good 20 years ago and they still look great today (ex. a Lin turntable). Facel-lifts, meters, gadgets, are extraneous (ex.Krell) and the cost is passed on to the customer. The "old" yellow-and-black Rolls that Arther had looked better than the ones they're making now. Just making a point. 

@bo1972 

I've never heard of Tru-Fi, is this a company, something you sell/rep work for?  Just never heard of it.

Tru-Fi stands for True Fidelity. You want to hear all your music as it sounds during the recording. Sound contains different aspects/properties. All different aspects of sound can even influence human emotion.

When you would read about how our emotion works regarding music you will find out that there are 3 aspects that influence our emotion during listening to music. We do a lot of research in sound all the time. As we use many modifications on amps, preamps, sources, power supplies and subwoofers. 

When you judge most audio products on the aspects/properties they can reveal it becomes very easy to understand what is missing and what can be heard. Most people do not understand why their system does not give them the emotional feeling they are looking for.

When you would know more about sound and how the human emotion works it becomes clear why most systems lack emotion. Diversity (lagering) in sound is the most important aspect of sound. Due to the fact that this part can create the biggest influence on our emotion during listening to your beloved music.

But when you would judge most digital sources and even amps these days on this part, the facts (the sound you can perceive) prove how limited the layering in sound is. When a system can only create a low or limited level in diversity in sound all human beings will not feel a lot of emotion during listening to their music.

When we let new clients hear their own beloved music with a Tru-Fi system, they feel and understand the huge difference in emotion. We use different songs to teach people what layering in sound is. And what it does to their emotion.

We use many different songs to explain the aspects which they miss in their system. We want all audio systems we create and adapt to be able to reveal all the aspects of sound. And what it does to all people is always the same. They use their system so much more frequently and longer at the same time ever before.

Tru-Fi proves on facts that it outperforms any created system by trial&error. It also proves that you need all the aspects of sound to be connected to the music. And experience the emotion the music possesses.

@dep14 Uh-oh, you just went down the rabbit hole. 

@dgarretson

I was just making sure I could smell what the Rock...was... cookin!

I will say however, right now my wife and kids are not home, I am in my audio room with my 250.8, XP12, and my Ohm Walsh 5000’s and getting my dose of Metal and Classical all at once. Metallica S&M.

Feeling pretty emotional listening to Metallica and the SFSO rock One, just knowing Sandman comes next and closing with Battery.

Of course, that could be the emotion of pure Joy,  90+ db’s and no one to tell me to turn it down.