Summary:
I switched to tube amplifier after hearing the Jadis DA-30; the sound evidence coming from that amps is really different from what I heard with real state amps.

I did not compare it to many other tube amps, but it was the best in its price class in retailers shop.

I upgraded tube to KT-90 2 years ago, gaining some nerve while loosing some power which does not really matter with my 93db BC acoustique.

the only drawback I know is about the bass register which may sound weak in the 30Hz-50Hz area and emphasized on 60hZ-80hZ area; but it mainly depends on the room in which it is.

I would not use this kind of amps for hearing rock.

But as I mainly enjoy with jazz, vocals, classics and world music, I have not yet found a better amps since.

Strengths:
medium and high frequencies

Weaknesses:
Every weakness of tube amplifier : it must be cooled; you have to wait half an hour before getting the best of it.

Similar Products Used:
Kora Design 30
Marantz PM 17
Arcam alpha 10

Summary:
Collecting Tube-Amps, mainly Single-ended Triodes, I bought now my second DA 30.In Comparison with the fabulous JA-30 and JA-80 or Shindo amps the small integrated DA-30 sounds a little bit boring. even not so good as my first one six or seven years ago. High frequencies and dynamics are not more than average, the midrange is very good indeed and the bass is as it is with the 6550 tubes - not bad.
I`m missing the transparency, that parts good amps from the best.
Speaker: The wonderful Dynavox horn
Turntable: Wilson Benesch with Denon DL 103 and Audio-Research Phono
CD: Copland 289
Cables: Fadel and Argento Silver

Summary:
The typical jadis sound in a marvellous amplifier, for a relative low price in this category.But the most important is that it sound perfectly. For me, the best of his class. But, if you want to enjoy with it, you would have to choose same high quality componants.
Try with some very good english loudspeakers (Acoustic Energy AE1 or Royd Sapphire at low price) and CD player (Arcam Drive, Deltec converter)or canadian tuner (Magum Dynalab Etude),amazing!