Hifi Choice (January 1994):
Audio and Techniek no. 39:
Hifi News and Record Review July 1996:
Hifi Video Test, May 1995:
My own observations
Something which is obvious, and mentioned by the magazines as well, is a very good midrange. Reproduction of vocals is supreme. The mids integrate with treble and bass very well. I would summarize it with very coherent sound characteristics, which excells with acoustical music. The amp has "fun" performing music. It has a good live-performance, a good drive. The stereo image is very good as well, broad and deep.
The original amp also has some draw-back. The otherwise excellent seperation between sound sources is less obvious during loud passages. Treble is a bit on the shrill side (which is mainly caused by the National tubes supplied). Bass performance is OK, but less controlled than with my solid-state Marantz PM-54 amplifier. Electrical (harsh!) music sounds too relaxed with this amp, it misses punch. But there is a trade-off, because music which sounds humming or bumpy otherwise, is less stressful.
I've compared this amp with an Audio Innovations 500. It is on the same quality level. The 500 sounds a bit more "romantic" or "fluid", the Classic is more towads the analytical side. It depends a bit on your taste, mood, or the type of music which sound you'll prefer. Personally, I prefer the 500 a bit more, but I've also heard people telling the other way around.
My conclusion is that this amp has a very good price/performance ratio. I've hardly heard competitive amps at price ranges which are even twice as much. I think it's therefore a pity that this amp isn't fabricated anymore.