Pass Labs x350.5 & Classe ca-m400 class a power?

Thanks everyone.

Teajay, as you pointed out auditioning amps is a major pain. So I am trying to do as much due diligence to narrow down the choices before I try and drag home a 100+ lb amp home. Thanks for your input. I really do appreciate it.

Tboooe, both the Pass Labs X-350.5 and Classe Cam-400 are excellent amps that offer great build quality and wonderful sonics.

That being said, I have heard both in my system, and find the Pass Labs amps to offer a "musicality/natural" quality that I did not find in the Classe amps.

At this level of gear, it really comes down to personnal taste and system synergy. The only way to really decide is a home audition, you can keep asking for informed opinions, but your own ear's have to guide you.

Since, I use a Placette dual active line stage, I can't be informative regarding the Pass Labs pre-amps, it's been to long since I last had one in my system.

Historically, I had Aleph's 1 before the 350.5 in my system. When the X-series amps came out I auditioned a 350 and found it quite dynamic/detailed/transparent, but somewhat "cool" and less musical compared to the Aleph's, and therefore it was not my sonic cup of tea.

The 350.5 has all the virtues of the first generation X amps, but adds good taste of the "warmth/musicality" of the Aleph series.

I'm excited that later this week I'm going to be auditioning a pair of XA-100 monoblocks, to power my midrange and ribbon tweeters of my MG-20R's.

Like you, I have gained all the information I could by
talking to other fellow audiophiles regarding the difference between the .5 series and the XA series, but now I have to hear them in my system to really tell what the difference is and will I like the XA's sonics better then my 350.5's performance.

So, I think the time has come for you to set up some home auditions if possible, its both fun/exciting and at the same time a pain in the ass, but the only real way to tell. When I last did this with power amps I auditioned five different amps before I got what I was looking for.

Finally, for my ear's, with my gear, the Pass Labs X-350.5 is just a beautiful sounding piece, and somewhat of a bargain at its price. I believe you got to spend alot more, such as 600.5's or XA series amps, to get a better sounding amp and how much better is open to speculation.

Cdma, my recollection is that pure class A amps pull twice rated power, but I'll look it up. In any event, as true single ended amps the Alephs (except the 1.0, which has an auxilliary pull stage) cannot leave class A and remain linear.

They do sound great.

Ghostrider,

As I know, Pure Class A amps draw four-time their rated power from AC line constantly, while Aleph three-time.
Aleph got my vote too !

Tboooe, of the pairs you've suggested I can only say that I own the X1, and have heard the x350.5 (but that was not in my system). The X1 is an awesomely quiet, very neutral preamp. Nicely extended in both directions, with a very nice midrange. It is one of the best preamps I've ever heard. There is another thread where it was remarked that - in comparison to a great tube preamp - the X1 mids are thin and bare. Frankly I can't agree. I'm not sure how much system dependency the X1 has in placement with other components, but in my system (driving a Van Alstine FetValve amp) I get a satisfactory midrange indeed. Tonal colorations, a real organic presence.

My recollection of the x350.5 is that it is also a fine sounding piece of gear. It was being driven by the X2.5 and I thought the pairing sounded very musical. Maybe just on the shady side of neutral. I can't remember what source was being used, though.

My only complaint with the X1 is that the gradation between the volume click stop positions is too large (about 1.25 dB).

By the way, I am considering the X1 + x350.5 or the CP-700 + CA-M400. Any thoughts in these pairings?

Thanks everyone. Honestly, I am undecided between the Classe and Pass. Those of you who recommend the Pass, can you please let me know why you think it is better than the Classe? Who has been able to directly compare Pass and Classe?

Single ended means that a single active device(or paralleled set of active devices) handles the signal. The active device could be either a tube or a transistor.

The alternative to single ended operation is push-pull, where one active device (or paralleled set of active devices) handles the positive parts of the waveform and another handles the negative parts of the waveform.

For audio use, a single ended stage must run class A. A push-pull stage can run class A or class AB, depending on biasing. In pure class A operation, neither device in the push pull pair ever shuts off.

In class AB operation neither device in the push pull pair shuts off on small signals but on larger signals one device is off while the other is processing its half of the waveform. Effectively the amp runs class A for small signals and transistions towards class B as signal strength increases.

The higher the bias (and the hotter the amp runs) the longer the amp stays in class A before moving into class AB as the signal increases.

Pure Class A amps are inefficient and draw twice their rated power from AC line constantly. The power draw is independent of the amp's output and most comes back as heat. They are space heaters.

As I type this I'm listening to a pair of Pass Aleph 1.2 single ended mosfet monoblocks. Each is pulling about 500 watts from the AC line and the room temperature has risen 8 degrees in the last 2 hours. But they sound divine!

I vote for Pass also.

Tpsonic: I agree about the sonics... get the Pass 350.5

or get the 250.5 and get a X1 preamp... Remember the preamp is just as if not more important than the amp in transparency.

Regardless of the number of class a watts,get the Pass before the Classe.Sonics and dependablity will never be an issue.

Hi Teajay, thank you for the response. Can you explain single ended class a vs regular class a?

Tbooe, the 350.5 has fifty watts class a before it goes into class a/b. It also offers, in its first few watts, single ended class a before it goes into regular class a watts.

That's way it offers some of the "warmth/musicality" of the XA series.

Don't know the specs regarding the Classe amp.