Moscode 401HR vs Pass Labs X150.5

So...for those that followed my previous thread, I am still in the hunt for the best amp under $2500 (after auditioning and returning a set of mono amps). I really have not been able to find much on the differences between these two amps sonically. I know the Pass has better resale value, but that's not my primary concern, although it is a concern for sure. The Moscode is rated at 200w into 8ohms (300 into 4ohms), the Pass at 150w (also 300w into 4 ohms I believe). I also know that Moscode improved upon the 401HR with the 402AU. Anyway, my tastes are bluesy rock, female vocalists and jazz. My system is as follows

AIFF lossless => Peachtree Nova USB DAC/Preamp => ??AMP?? => Dynaudio Contour S3.4 spkrs (4ohm load, 88db)

If anybody out there can offer comments as to how these two amps compare (or don't!) I would appreciate it. Thanks
I owned the Moscode and it is very nice but be careful of the impedence (speakers). It is not recommended for 4 ohm speakers (even by Moscode...also see the Steriophile comments on the speaker impedence). My speakers are just a tad above 4 ohms and the result was a softening of the top end and a bit of looseness in the bottom. The mids were fantastic. I ended up preferring a solid state amp in my rig for the reasons mentioned above (put the tubes in the preamp). Just my thoughts....your experience may be different.
05-24-10: Jeffga
It is not recommended for 4 ohm speakers...
That's not accurate.

The quote from John Atkinson's Measurements section of the Stereophile review states:
The Moscode 401HR offers pretty good measured performance, though it is clearly not happy driving loads below 4 ohms.
The difference here being *below* 4 ohms. If you read the measurements section, you will see that the amplifier did fine into 4 ohms, but faltered into 2 ohms.

The OP's speakers have a minimum impedance of 4 ohms (even though they are marketed as 4 ohm speakers, which usually means 4 ohms *nominal*).

I don't believe the Moscode 401HR will have any problems with these speakers.

That said, I am not recommending the Moscode over the Pass Labs, or vice versa. The choice is an issue of subjectivity, IMO.
Never heard Pass, but the Moscode, which I've heard twice, sticks in my mind as an exceptional amplifier. One I would probably buy if I had the money. YMMV, of course.
Both are fine amps and do have sort of a similar sound. I have owned several older Moscodes in the past but do not miss the expensive repairs. I have owned 3 different Pass Labs amps and driven them with very difficult loads and never had a problem. The circuitry in the Pass is much more simple and stable. The more challenging loads seem to eat the Mosfets in the Moscodes and Haflers. It was 12 years ago, I had a pair of Infinity 8 Kappas and a moscode. I was very luck to find all the parts to fix my 8 Kappas when my moscode expired. It happend again 2 years later with a Hafler 9505 transnova. My technician friend said he was shocked that although both amps had different parts the output section was the exactly the same design. He also pointed out what made the Moscode sound so good was an exceptionally well designed and beautifully buit input stage. The Pass will sound as good or a little better but will be more reliable.
I have yet to hear or read about any reliability issues with the Moscode 401HR. In this community, I would think any reliability problems with the latest Moscode amplifiers wold have surfaced.

I don't believe one can apply the reliability of Moscode amps manufactured 12 years ago with the latest offerings.
I sure they are better today. They are still a Hafler designed output stage with a really good tube buffer or input stage. Look at how much stuff is tucked inside both the newer and older Moscodes. The caps are tucked sideways because of the tight real estate. Heat on amplifiers causes problems over time. I sure you are right they are more reliable today than from 12 years ago. Here is a link to a pic of a newer moscode amps.
The Infinity Kappa 8's were commonly referred to as "amp killers," although not quite to the same extent as the even more notorious Kappa 9's.

If you don't mind looking at a Julian Hirsch review, on the second of the pages linked to below see the lower part of the middle column, and the top of the third column, for a description of its outlandish impedance characteristics:

-- Al
Almarg, how do Infinity Kappa 8's relate to this thread? The OP owns Dynaudio Contour S3.4 (4 ohms, 88dB).
Almarg, how do Infinity Kappa 8's relate to this thread? The OP owns Dynaudio Contour S3.4 (4 ohms, 88dB).
Tvad (Threads | Answers)
Nevermind...I see Thesoundhouse owned Kappa 8 speakers back when he owned early Moscode amps.
Any interest in the roland model 2 and 3's that are for sale;I have model 6 mono's and they drive my soundlab m2's and usher rw729 extremely well and have the tube like sound as well.
With an 88 dB and a 4ohm load the Moscode will probably be OK with the Dynas. I had a chance to listen the S5.4 and they do sound good. I asked my audio tech friend and he said S3.4 should be fine with the newer moscode amps. He thinks the chasis set up is too tight and will over time need service because of the heat. He also pointed out that He is glad that Moscode are now using newer output devices but it is still a Hafler design with a tube input stage!
Grant (Tvad) I always appreciate your thoughtful and on-point responses. Soundhouse, I appreciate your experience withthe older Moscode amps and your comments as well. I decided on an ARC 100.2, which saved me about $800, and fit into my equipment rack. It sounds very very nice on some recordings, but not so special on others. Like some days it makes my jaw drop and others, well, it sounds good, but not jaw-dropping. Maybe Im nuts, but the sound seems inconsistent. Is this possible? I thought amps basically either worked or didn't work.
The ARC 100.2 is likely revealing the differences in the recordings, which any good amp or component is supposed to do.
Also, much has been made about fluctuations in the quality of electrical power from day-to-day and even hour-to-hour. Perhaps the ARC is more sensitive to this than other designs? Maybe auditioning something like the PS Audio Power Plant is in order. Just an idea.
Bondmap, that's a great suggestion! I was considering something like that. But now I will pursue it more earnestly!
Before you invest more dollars into components other than an amp, why not measure your voltage at the outlets with an inexpensive multimeter to learn if in fact you are experiencing voltage swings.

Do you have all your components plugged into the same outlet? If not, try it. Use a simple household power strip if necessary.
Tvad's idea is solid, but if you are mortified of electricity like me, most power products, including the PS Audio, are available either direct or from resellers that will offer a generous return option. If the device doesn't fix your issues, just return it. You could be out shipping charges, though.
You guys are great! The electrician is coming Tuesday with a multimeter and we shall see what the story is. Regrdless, from what I have read on the PS Audio Premier Power Plant, I have no doubt that would both protect my gear AND noticeably improve the sound. But first things first. Its just a question of where my limited funds are best spent now.
Well, the electrician came by today and tested all the outlets, circuits and breakers.... Long story short, he will be replacing the breaker that controls the circuit on which my equipment is running. And I am going to run an extension cord from my power strip (into which I have all of my source compnents plugged in; TV, Comcast box, DVD player, CD player, Laptop, External Drive, Wii, and Squeezebox) into an outlet which runs on another breaker in another room.

Bottom line. My electrical is fine for an apartment building, which by its very nature has inferior voltage stability to a freestanding home). He said I may have too many things running on the same circuit. So, I will leave the amp, the Integra pre-pro and the Nova (preamp/DAC) running on the current circuit with a new breaker. And the rest will run on another circuit. This may improve things. It certainly shouldn't hurt.

I can always buy that PS Power Plant... Or buy another amp and see what that does.
UPDATE: So... after receiving my Peachtree Nova back from service two weeks ago, I am happy to report the following;

1) On the advice of Johnny Rutan and Wally from Underwoord Hifi, I attached a cheater plug on the end of the power cord of the ARC 100.2 in an effort to squash the annoying buzz/hum that has been plaguing my system since the amp's arrival. And....SUCCESS!! Dead nuts quiet. Cost: $5.99 from Radio Shack.

2) I purchased a pair of higher quality interconnects from Paul and Judy Speltz at AntiCables with the Eichmann bullet plugs (all copper), and boy what a difference. But still, my system was still hovering in the "average" zone, albeit the high end of that zone. Cost: $150

3) Finally, I purchased a French-made Phillips 6922 tube from Brent Jesse per Brent's recommendation to replace the stock tube in the Nova, and - I TRULY can't believe this -... I don't know how else to say this.... but HOLY F--KING SH-T!!! Suddenly, the bottom end and mid-bottom range opened up, deepened, sharpened - I could hear the subleties of every note coming from every bass instrument on every recording I played, The soundstage expanded to fill the room, the dynamics were explosive, the texture of strings, harmonies and voices floated through the air and resolved naturally into space. It felt at times like the entire band was playing in my room, and at other times, like just a single performer was singing or playing from like seven feet away, five feet off the ground and maybe three feet left of center. It was eerie! It was AWESOME!! Thank you Brent!!! (Of course I am neither affiliated with or related to Mr. Jesse in any way, haha!!) Total cost: $110.

I would say to every Nova or Decoo2 owner out there, (so much for pleasantries) you are an IDIOT if you don't swap out the tube in the Nova with this one! For an extra $100 it is like I now have a high end tube preamp that is allowing the rest of my system to shine through. For the time being, it appears my worries and frustrations are over. Thank the Lord - and thank ALL of you for your kind, thoughtful and helpful suggestions in my quest for audio nirvana. The Audiogon community ROCKS!!

I now surrender the podium. Happy listening to all, and to all a good night.
Fredorama, it's good to know you've made some inexpensive adjustments with big gains.

Grounding issues (hum/buzz) are a PITA. One would think that for the cost of the gear we own, manufacturers would employ grounding schemes that work interchangeably, but such is not the case. Grounding schemes among manufacturers is not consistent, and this contributes to ground loop problems.

Some of my gear has been absolutely quiet, and other gear has been noisy regardless of how many hoops I've jumped through.

I recall that I used a cheater plug on my Moscode 401HR, which knocked out all the noise.

Of course, you realize that using a cheater plug is not recommended as a long term solution. However, when there's no buzz, and you've spent hours and dollars trying to eliminate the buzz the proper way and it still persists, then the risks of using an effective cheater plug sometimes seem worthwhile.
You got that right Grant! Finally a hum-less, buzz-less system that I can live with. I'll take it. Thanks
I do not understand how you can buy these amps in under $2500, but I am guessing you would be going the used route. In that case try to find a Symphonic Line RG1 MK4, it will probably end your search for a power amp for a long time to come (till you have the funds for a higher end Symphonic Line).
BTW, the RG1 is stable at 1 ohm.
Thanks Pani. I was considering a Plinius SA-102 for a while. Apparently, based on your thread, you were too. I see you settled on the Symphonic, which I am now reading about. You have piqued my interest. Thanks!
I have owned the 402au and the 402au and 401hr.
Resale value of 401hr-close to what I paid for it w/o advertising.
Heat and reliability- no problems. The 402au arrived with one channel dead. A wire had come loose in transit. A call to George and I was told to reconnect the wire. I plugged it in and no problems since.
Yes the 401hr ran hot. the 402au solved that problem. I don't know how. I don't suspect the heat is a problem in the 401hr. The heat is generated by the mosfets that are mounted directly on the heat sinks outside the other components.
Circuit layout-Always a judgement call. I like the fact that my amp sits neatly in my cabinet. See speedfreak on virtual systems. The trend is to minimize the footprint
My speaker is the ML CLS. A much more challenging load than your speaker. No problems.
Like TVAD I can't ell you which way to go. Obviously you know what my choice would be. If you like solid state PASS is one of the best. A little too smooth for my taste. The Moscode just sounds more like music to me.