Is the moscode 600 a great amplifier?

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.