Price Paid:  $0.00

Summary:
The Graaf GM20 is out of production forever now but remains one of the very best amplifiers around.

Having said that, there are some serious issues with it. The amplifier does not have auto bias and because of that it needs to be serviced at least once a year. If you are not comfortable to set the bias current and offset yourself, you need to visit a dealer. This is, however, essential, not only for the sound quality but also to keep the tubes in perfect condition. If you do not do this, you will inevitably destroy your tubes.
Another 'thing' with this amplifier is the need to find suitable accompanying speakers. The best sounding ones have a high impedance (> 6 ohm) and a high sensitivity. Some folks try to circumvent this by transforming the GM20 in a mono version. But then you will need two amps and twice the amount of tubes (why then not go for the GM100?). There is no real need to do this because there are some good speakers around.
The last issue with this amp is that it runs hot. With four beefy 6C33's, the GM20 is not something you want to expose your small children to.

Why then is it worth all this trouble? Simple, because the sound of the GM20 is very, very seductive. It has a lovely tube (triode) sound but at the same time it is very open, fast and controlled (OTL characteristics). Some people think the amp lacks bass response but I do not agree. This OTL does not come with the down side of (old-school) transformers and is in fact very competent in the lower regions. But, as said, it is sensitive for the choice in speakers.

I own one for 7 years now and I have never considered buying another amplifier.

New ones will be hard to find as Graaf does not produce them anymore. I think this is a shame and I am sure that Graaf also think of it in this way. I guess that the service requirements made Graaf change it's minds at the end. The GM20 is not just a plastic box that will let you enjoy music for many years without any care whatsoever.

But boy, if you take good care of it you will have a winner.

Price Paid:  $5500.00

Summary:
I have listened to a number of amps, this amp releases a huge soundstage with extremely realistic vocals, strings, bass strings. The feeling is soothing and elegant. This is a wonderful sounding amp , very quiet, reveals all musical details, female voice is spectacular with this amp, I am using it with:
Sonus Faber Guarneri speakers (best)
Graaf 13.5B preamp
Cyrus dad3q cd player
Cyrus fm7 tuner
Monster sigma retro gold cabling

Strengths:
Soundstage very high and wide.
Quiet and clear, beautiful midrange

Weaknesses:
Needs at least 30 to 45 minutes before warming up. Maybe a little more bass, but not bad for only 20 watts.

Similar Products Used:
YBA 1, audio research vsi55, unison s2, copland 505, shanling stp80, unison unico i (Graaf is much better than all of these, also looks much nicer to)