Is the moscode 600 a great amplifier?

Hi there,

I'm planing to buy a Moscode 600 power amp. I found a lot of reviews on the web, but they're quite mixed: some are lukewarm if not bad (a reviewer said it's a "low" fi!!), others are nice.
Anyone can tell me his experience with this special amp? In particular, does it really match well with inefficient speakers?


It is a very good sounding amp but cheaply built.
it is a very good amp
I had one in 1987. At the 4/5/600 they sell for they are ok. At that money you get what you pay for. I had the ics and binding posts changed out. What they used is pretty bad. While it has tubes it is not a tube amp. It is a mosfet output design. Mosfet mist included.

For additional info that may benefit the original poster I heard the new prototype Moscode 402 with a passive stage integrated in the amp. In my humble opinion, this pre/amp is going to make waves based on what I heard. I was not the only one with this opinion in the room at the Home Entertainment show in NYC.
I also heard the Moscode 402 hybrid amp on the Joseph Audio speakers.
That system sounded impressive.
It sounded sweet and smooth.
The Joseph Audio speakers sounded much better this year then in years past at the show.
Thanks for the responses. Avguygeorge, when you say "At the 4/5/600 they sell for they are ok", does it mean that in absolutes terms you don't consider it as a good amplifier? If so, why (refinement, reliability...)?
I'm looking for an amplifier for my ATC SCM20 (actually driven by a Michaelson&Austin TVA1) which are watt hungry. The 300 W of the M600 seem OK for them, but are they nice?

Concerning the 402, thanks too, but I live in France where there's not distibutor I'm affraid.

I was auditioning a pair of speakers and heard the Moscode head to head with the Van Alstine hybrid amp. The Van Alstine smoked it.
I have had mine for almost 20 years.It is very reliable,a good match with current hungry speakers.It sounds much much better when used with Speltz Zero autoformers.
Sound is mediocre minus-but warm with mosfet mist.
Good, powerful amp. Let the price speak for itself. A 300 wpc amp for what moscodes sell for???
Several years back, I owned the Moscode 300 (in fact, two of them). I had the opportunity to compare a burned in 600 with the 300. To my ears, the all tube 600 sounded somewhat soft in comparison with the hybrid 300. It simply lacked the life of the 300, and I quickly found myself dissatisfied with its presentation. This said, the old tastes differ assertion might apply here.

What speakers were you listening to and what did you like better about the Van Alstine? Thanks for any info.


The speakers were Salk Audio Veracity HT3's. The Moscode was not the 600, but a new one that is getting raves.

By comparison the Moscode seemed dark. The Van Alstine amp was very musical. Nice tonal balance all the way around. For the money, Van Alstine is a real giant killer. BTW, I don't own any Van Alstine gear.

I have neen looking for this comparison for awhile and whats even better is you heard them on the HT3s which is the speaker I use.

Thanks again Larry
I have owned a Moscode 600 for ten years until I sold it, bought it new and I always thought it was a great amp. With the right tubes it will knock your socks off. I have to disagree with the person that said it was cheaply built, it was solid and in the ten years I have owned it never had it worked on. Moscode advertised it as a hybrid, tube input mosfet output, and for the money you could not go wrong
I bought my first 300 back in the mid 80s to replace an Ampzilla which, by comparison, was thin sounding, lacking in detail, weight and resolution. Since then I have purchased a used second 300 and 600. My career began as a musician and these hybrid amps sound like music. I later became a recording engineer and the Moscodes are my "go to" reference amps in my out-of-studio system. I run a set of Martin Logans and Maggies with them. In my opinion you can not approach the sound of the Moscodes unless you spend lots of bucks...., lots. they are one of the finest sounding amps ever built and represented a bagain at the time I purchased them. Neither have given me an ounce of trouble in all the time I've owned them (Over 20 years), save for a change of tubes.

A few reasonably priced amps that come close are the Hafler 9300 & 9500 series or, if you can find one, or a Quad 606 or 909. Of course you'd have to find the Haflers or Quad 606 used. The Quad 909 is still made.
I had mine modified by George Kaye years ago, which made it a much better amp. Much cleaner sounding with better detail and bass, more extended treble, but still nice full midrange.
Compared to today's better amps not as transparent, but still a classic.
I bought both my 600's in the late 80's and had the first one modified in the 90's.

There are a number of advantages to the modified amps. Better binding posts, and inputs as mentioned above. The protection circuit is taken out of the audio path, and on, and on.

But even the stock amp is very good.

You can come very close to the current Moscode at a fraction of the price. Some of the mods are easily done by a moderate DIY'er.

If modified (by George) you can do a lot of tube rolling.

I have Russian NOS (1979 & 1982) 6H30p-DR in the input positions and Ediswan NOS EC88 in the driver position of the channels connected to the stats and 6GU7 in the drive position of the woofer channels.

Tube regulation DOES make a difference (therefore the 600). With Martin Logan Prodigy and ribbon super tweeters I still don't hear MOSFET mist. It could be my ears or my setup with the modified amps.

Perreaux, Belles, Pass and other well thought of (including the new Moscode at $6,500+) use MOSFET output.

Just as SS doesn't necessarily have to be hard and brittle or tube don't have to be sweet and gentle. I don't believe all MOSFETs have to be "misty".

My system with two modified NYAL Moscode 600's;
As to comments above about Autofomers.

The 600's always sounded WONDERFUL into dynamic drivers, modified or not.

When I first went to E-stats they did NOT sound that good. I almost got rid of them. I went to some VTL mono blocks (160) they were only marginally better. It wasn't entirely the amps. It was partially the entire system.

In an effort to get the VTL's to sound good I eventually went to autoformers. It did not do much for the VTL's but I eventually brought one of my Moscodes out of a year's retirement in the garage and tried it with the Autoformers. Holly ***t, there was the glory of the Moscodes that I remembered, as I upgraded the system, including speaker wire, the Moscodes eventually sounded better without the Autoformers and I moved them along.

So, given the speakers you are using, a good Moscode 600 will kick ***t and two in vertical biamp should blow you away.

Hope that helps.

Can someone tell me what Mosfet mist is?
It's just a term used for the lack of transparency some MOSFET amps posess Baranyi.
Replace the tubes with either Siemens E188CC/7308 or CCa, and the sound will be transformed greatly. Then there's the upgrade path as well: ( People don't ususally bother with modding products that aren't worth it in the first place. If you are stuck on SS amps- Don't let the slight "mist" of the MOS-FET bother you. That's a great improvement over the grain, glare and edge that bi-polar transistors exhibit. Yes- The Hafler TransNova 9505 is a great SS amp also(I power my woofers with one). FET front-end instead of the tubes, pure class A, fully differential, and MOS-FET outs(also slightly "misty". That "mist" takes a trained pair of ears to notice, BTW.
Perception seems to be one of the most determining factors for what people hear. But most designs can sound good, even MOSFETs.
The amps are even better now. Remember these are a pair of the Max mods that George Kaye does. I have Russian NOS ('79' & '81') 6H30p-DR in the four input positions. I have four Amperex Bugle Boy 6DJ8s (early '60's' in the four driver positions. And a Pope NOS 7 yes 7DJ8 in the regulator positions.

The amps are heavenly.
It is powerful, reliable, and more tube like then transistor.
It drives just about any reasonable load, and even some unreasonable ones.
IMHO, it is THE amp to have if you are a guy like me, always changing, or owning many pairs of speakers.
The Moscode 600 is a LOT better amp then a Moscode 300.
The Moscode 600 can be tube rolled to sound like you want it to.
This means you will not have to buy a new amp to get your new speakers sounding right.
Simply roll the input tubes of the Moscode 600, and change the sound as you wish.
They go for around 600 to 800 dollars.'
At that price, it is a no brainer.
One further thought on modified and tube rolled Moscode 600's.

George once told me that he had bridged some 600's for a famous record maker (to remain un-named), because that is what they wanted. However, in his opinion they did not sound as good bridged as they did vertically bi-amped.

Never the less, based on experience with a different pair of amps in the late 70's. I kept trying to bridge them.

First I used a transformer input. Interesting result, but George was right. Later I bought a SS bridging unit with absolute polarity switching, still not as good as vertical bi-amping.

Eventually I bought a preamp with balanced out, but no absolute polarity switch. I built a little box to convert the balanced out to single ended with switches for absolute polarity. The box also gave me the ability to bridge the amps.

WOW, WOW, WOW!! That was what I was looking for.

I now have two preamps with balanced out, one SS, one tube. They both do a fabulous job of bridging the amps into 1000+ watt monoblocks into an 8 ohm load.

The good news is that the amps were originally stable into very difficult loads. Because they are bridged into a pair of Martin Logan Prodigy they need to be stable. These speakers are nominally 4 ohms with a dip to 1 ohm above 15kHz. Running the amps bridged the amps effectively see 1/2 that load, so a dip to 1/2 ohm.

If you are willing to do a little, to a lot, of work with them the 600's can really shine.
Its a great amp.
I have Martin Logan Prodigy as well .I was under powering them with 80 wpc Luxman and they sounded great(but now I know bass light).
After blowing up the Luxman 3 times I figured I need to get more power.
Saw the 600 Moscode used and took a chance.
It sounded bad with my SS Yamaha phono preamp highly regarded .
Put in the Moscode Minuet in A preamp and wow sounds good.
After tweaking with nos Mullard 12ax7s and 6dj8s in the pre .
NOS Amperex BBs in the amp.
I have live music in my living room.
I go to a lot of live jazz venues and my living room now sounds better than live.
My quest is satiated.But being a tweeker Ill still try to improve it 0.01%.
But if you are wondering how a Moscode 600 and Moscode Minuet In A sound with Martin Logan Prodigy .
Its better than live venues.
Mosfet mist is defined as the veiling of the highs. However when Mosfets are employed in a well engineered product they are extremely good sounding.

Does anyone know what I can buy a cage for a 600 I've just seen one online for sale..its modded but doesn't have a i'm in two minds as to buy it or just wait for another one to show up with a cage..he also wants $995...which I think might be a little too high with out the cage

Any advice or info would be much appreciated!

I have a fully modified (by George Kaye) NYAL Moscode 600 amplifier that I have owned (and enjoyed) for several years. However, my efforts to contact Mr. Kaye (via email and telephone) of late have repeatedly failed.
Two questions, if I may, for the Moscode aficionados here on Audiogon:1) Where can I obtain a quality tube replacement set for the 600; and2) Should I need service for the amplifier, where may I turn?