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

pistha, while you were talking with Pass Labs did you ask them their opinion regarding the XA25 driving your Sophias? I ask because I believe my speakers also dip rather low although I only know their nominal impedence.

A few years ago I bought a pre-owned Pass INT-150.   I replaced a Wyred4sound 4 channel amplifier, because I no longer needed to bi-amp.  Talk about going from apples to oranges... The Pass was kind of an impulse buy.  I did not compare to anything else at the time.  I can't really come up with any weak points other than that yes, they do run very warm.  That is intentional though.  I don't plan on changing unless some other system change forces me to.  I can envision a scenario where an integrated would not be appropriate, but for my system now, I prefer the convenience and the sound synergy of the Pass integrated.

Expensive, Big,run hot also cost a lot to run, forget Solid State, have a listen to a Nord Acoustic mk11 class D with the REV D upgrades, you can choose various OP-AMPS depending on ones taste or system, you can buy all the various OP-AMPS and find which ones suite your taste its called OP-AMP rolling,

Phone Colin he sells direct worldwide and prices are very reasonable, my Nord One UP SE NC500MB mk11 costs approx £2000 and sounds amazing no faults at all, its xlr only, 

Then find yourself a good pre-amp with the money you saved I recommend Townshend Audio  Allegri + no need for expensive power cord or conditioner, no mains noise, its single ended only, i use Cardas Clear female rca - male xlr the combo sounds incredible for £4500 

Check out the review of Allegri + in Positive Feedback and Nord Acoustic stereo amplifier in HIFI PIG and Six Moons 

I do not know Troy and have never shopped in his store. I enjoy his posts. While he certainly has some motive to promote the brands he sells, his thorough and knowledgeable insights allow me to learn about large, heavy and expensive gear w/o having to buy (and sell) everything out there. I purchase from (the few remaining) brick and mortar stores locally as well as from retailers and private sellers on A-Gon. I do not post very often these days, but do read many of the A-Gon threads. At 61, & with a bad heart, my audio addiction has become more difficult to feed. I no longer find it at all easy to transport, unbox, set-up, re-box and ship large and heavy equipment. Thanks to Troy and others who post and provide insight to the fine Audio gear that is becoming more and more difficult to hear in stores and audition at home.

I have owned different Pass power amps and mono amps. I had contact with Desmond Harrington (President of Pass Labs) for a long time. I also owned the XP-20. It is a good preamp, but not a stunning one.

When you judge Pass Labs on all the aspects/properties of sound. It will become clear that they lack realism in the individual focus of voices and instruments. When you listen to voices and instruments in real they are very small and direct. The Pass Labs preamp and power amp are not able to create the intimate focus as in real.

Desmond told me that the 0.8 series make voices and instruments smaller and more palpable. But it is still not among the best. In my world, it is only about the best possible. The rest is 100% useless in my world.

Voices and instruments are not only very small and direct. In real you can even hear the shape of a voice and instrument. I call it a High End ++ property. When you judge Pass Labs on this, it shows that it cannot reveal this part.

When I was in Munich at the High-End show in 2015, only one system of over 700.000 euro who was able to reveal a 3D shape of voices and instruments. The problem in audio is that most people who work in this world or see it as their hobby know very little about sound and music. Even most manufacturers have very limited knowledge and insight in sound in general.

When I talk with them about the acoustics, electro-smog, high-frequency noise and magnetism they still know very little. It becomes clear why so many audio brands and products are still sound so different than music sounds in real.

You need to understand all the aspects that influence both sound and stage. Sound is very complex and can only be understood and guided when you understand the influence of all these aspects. In all other situations, you still do audio by trial&error. This will always be audio without any real foundation. It can only create audio systems that miss essential parts of sound with also many flaws.