pass aleph vs x series

To some degree. The original X series sounded lean and cold, very much like stereotipical SS amps. But the .5 series adopted the Aleph topology for the first 50 or so watts, and added some of the signature sound that the Aleph are known for. I have an Aleph Os and an X350.5. When I upgrade to a new pair of speakers which allows for biamping, I am planning on trying to use both amps and see how it sounds.

But I think the air and dynamics are better on the X .5 series. (Take a with a grain of salt as I cannot compare them side by side. The Aleph Os just doesn't have enough juice to run my Thiel 3.6s)

FrankC

Got to jump in here. I own the Pass Labs X-150 amp(not the .5). I think "lean and cold, very much like stereotipical SS amps" is a bit harsh, but I understand what the previous response was trying to say. The X series is a little on the lean side through the mids, but it is not cold sounding to my ears. I have compared this mp to an older CJ amp, and while the CJ amp is much warmer and tube like it is not in the same league. I have had many amps in my system including some hybrids. The Pass amp has been my favorite. I have also heard the Aleph series, and while it is more natural and tube like through the mids it is not as extended on both ends and not as dynamic. I don't doubt the .5 series bridges the best of the original X series with the Aleph series if you can play in that price range, I'd go for a .5 series (or better yet a XA.5 series - real big $$$). I think the original X series sound great when mated to a warm sounding preamp that can drive the lower impedance of this amp. Happy hunting.

I am an Aleph owner and have heard the X series on several occasions. I have never heard the X .5 series. While "lean and cold" is a bit of an exaggeration, it is clear to me that the X series transmitted a small bit of electronic artifact that the Aleph series did not. This characteristic of the X amps was clearly apparent when listening. If the X series had more slam, more dynamics, more power, a little better bass control and certainly better looks, I had a hard time understanding why people were paying up to own it over the amps which delivered neutrality, smoothness AND resolution, all at the same time. The fact that Pass upgraded the X to the X .5 while describing the .5 as more "Aleph-like" in his literature and publicity is his acknowledgement that something was missing in the X series. I do not agree with anyone who says that the Alephs are not extended in either the bass or the highs. My Aleph 4 has plenty of bottom and can easily rattle floors with plenty of deep bass. The extreme high end is sweet, detailed and has beautiful clarity. Triangles and cymbals ride on top of the music with clarity and detail. They are simply present when in the music and you don't hear them when they are not. The high end, particularly the upper midrange, is not as prominent as some other amps and you do have to be careful as to what equipment and cables you mate the Aleph with, but all the music is there. This amp remains as natural and neutral as any that I have heard.