Pass Labs xa - .5 amps

Tvad, I was doing a search on the silverlines, (I've always wanted to hear them) and I saw several mentions where Alan Yun preferred tube amps. It might have been for a different model. Regardless, it sounds like you've sorted it out to your liking, and after all said and done that's the important part.
Just because the Pass gear didn't work for us doesn't mean it won't for somebody else. My new mantra: Listen for yourselves, people!

To be more exact, the result was a tonal imbalance with the highs louder than the bass and midbass, resulting in a tipped up or bright sound. The tube amps used were VAC MusicBloc 160 push pull and Atma-Sphere M-60 OTL.

Physically that might be explained by the higher output impedance of the tube amps. As output impedance nears that of the speaker then you will modulate the amount of voltage reaching the voice coil by the variation of the speaker impedance with frequency. For example, if the amp has an output impedance of 4 ohms then where the impedance of the speaker drops to 4 ohms you will get roughly half the voltage at the voice coil than you get at a point where the speaker impedance rises to 40 ohms (at 4 ohms half the voltage is dropped across the output of the amp while at 40 ohms only 10% is dropped). Obviously, if the speaker has been designed to be flat in frequency response when driven by an SS amp then you will hear a "tilted" presentation when played with a higher output impedance tube amp.

I am sure Tvad knows this very well - having directly experienced it and based on all his other knowledgeable posts here on Audiogon. So my comments are simply intended for those who are puzzled as to the cause of Tvad's observations...that's all.

In the example above we are talking like a maximum of 4 db difference this is not dissimilar from what some people might do with a tone control to adjust for room acoustics and preferences.

I found a good explanation here

Please note that if you have a speaker with a fairly flat frequency response (varies between 6 to 12 ohms) then differences in presentation from a low output impedance amp versus a higher output impedance amp will become considerably less.

It is not that a particular amp is right or wrong or a particular speaker is right or wrong => it is just important to consider the two (depending on your amp you might steer clear of certain speakers or depending on your speaker you might steer clear of certain amps. It is all about synergy.

fairly flat frequency response

Sorry my bad - I meant fairly flat impedance response.

I could definitely see where a Pass amp could take care of any perceived brightness....they certainly are market savvy.

I could definately see where a Pass amp could take care of any perceived brightness......they certainly are market savvy.

Chashas1, what do you mean by this comment? Have you noticed a particular characteristic of the XA.5 line? Or are you referring to Nelson Pass' marketing efforts? Thanks.

Oops, sorry, Tvad, I quickly perused a few reviews and saw a few comments on the newer esotec tweeter and assumed in certain situations it might be too much or would have to be matched correctly.

Peterayer, I definitely think they're market savvy as a company, just like any other that has been making money and stayed around for as long as they have. I think that's great. I wish a few others from the past were still with us. With my limited listening time with them, I can't really comment on their sound any more than I already have. I could tell that it wasn't for me, my list is growing longer. But isn't that the nature of the hobby?

Discussion lately about Pass XA.5 seems strange to me. Typical comment about Class A amp is that there is insufficient brightness, and not the other way around. I thought my XA60.5 does a fantastic job preserving the fair balance of upper frequencies relative to the mid and lower. An over-emphasis on upper frequencies grab your attention at first, as it gives you the illusion that the equipment is precise and detail in producing the sound. But you soon find out that the sound stage is hem in and the sound is rather harsh. I don't see that in the XA60.5 at all.

As to the lower frequencies, if you are looking for that extra dance club banging so that you can shake with the beat then there are many significantly less expensive amplifiers that can do that for you. As to the XA60.5, I definitely feel the jolt when the particular recording actually calls for it.

Pass Labs is not so much about marketing. Pass employs audio enthusiasts who appear to go out-of-the-way to help their consumers. Customer and technical support are among the top. Their products are extremely well built. They introduce new product lines every few years, only when an improvement has been made. And their products span the full range without being duplicative. Nelson Pass has a collection of white papers on amplifier design which are classic. He would probably be as happy helping you make your own amplifier as he would in selling one of his own. The equipment is respected and holds its value. This company is the real-deal in audio. Perhaps some feathers were ruffled on the dealer side of things in the past, but they seem to come through for the consumer.

I have had an x350, an x600, and an x600.5. When I was contemplating a change for my new set-up, I spoke to several people at Pass to discuss the merits of the xa160.5 vs. xa200.5, and found them to be responsive, genuine, and helpful. I decided to go in a different direction, but I could live with an amp from Pass. Not everyone loves the sound, nor does everyone have to. Personally, I do not quite understand the market for low-powered solid state amps. If others enjoy, then good. I think the x250.5-x600.5 are great amps that could be had at a good value. I also think the xa100.5-160.5 likewise are statement pieces.

There is no such thing as a perfect amp. We just have to find what works best with our systems. For now....

Tvad, Thanks for your reply....My earlier setup with small
room. Now I have apportunity to move a new flat which has big room. So,I am plan to change the speaker to floor stand. I believe that you have silver line speakers hence am seeking the suggestion, whether any of silver line
speakers (f/standing) can match with my xa 30.5. Also I need to know your speaker has esoter tweeter (of Dynaudio)?

Thanks Tvad, My new room size is approx 300 sq ft.
Let's try first my available setup... Secondly suggest for matching source becoz my current palyer getting old but well match with pass labs. Also that is 20bit n I need to upgrade 24 bit?