Nebelnest :
Cuneiform Rec.
Nebelnest : Nova Express (F,2002)***°
Cuneiform Rec.
Nebelnest : Zepto (F,2006)***°
Nova Express shows a somewhat heavy and energetic post rock RIO styled group influenced by Shylock, King Crimson and Univers Zero. Good musicians and clear ideas. Some similarities with Happy Family because of its heavy compositions, but with more high sound synths. Something for the more advanced RIO fans. "Zepto" also shows good progressive rock on the edge of RIO.
Opus Avantra :
This might be the only purely progressive item that can be also be described under this Chamber Music Rock genre. They were heavy influenced by contempory classical music, especially "Lord Cromwell plays suite for seven vices". My preference is however their first, "Introspezione (Donella del Monaco)". A similar Italian item in experimenting with various ideas is Pierrot Lunaire's "Gudrun" although I would not put that item into this page category. Opus Avantra is also listed here because a chamber music rock band plays the music.
Ozone Quartet :
This is the most rock oriented chamber rock music listed here. Nice violin-layers upon rock structured rhythms, half improvisational, somewhat song-structured with well crafted instrumental tracks.
The second album is most structured without loosing its fluently played character. It contains more professional studio work. It's "cleaner" and a bit easier at moments too. Progressive fusion music ?
Flat Five Rec.
Ozone Quartet : Fresh Blood (1997) **
Flat Five Rec.
Ozone Quartet : Nocturne (1999) **
Philharmonie :
Studio Chamber rock music.
Cuneiform Records
Philharmonie : Le dernier Mot (1997) ***
Present :
Present are harder and more experimental than Univers Zero. All albums are different. I didn't like the live recording from the beginning of the nineties, but n° 6 I found one of the best records of 1999.
Cuneiform Rec.
Present : Triskaidekaphobie + Le Poison qui rend fou (B,1989)***°
Carbon 7 
Present n° 6 (B,1999)****°
Carbon 7
Present : High Infidelity (B,2002)****
Label Carbon 7 : 
PSF :
Cuneiform Records
PSF : 279 (1990) **
Ruins :
A Japanese intelligent mind-blowing bass/drum/ vocal screams duo with almost impossible tempo & rhythmical changes. They started as a Magma-cover group and worked out their own style, which is often close to hard avant-garde. I heard most albums, but kept only the most inventive ones :("Vrresto" and "Pallaschtom" were a bit too hard for me)
Ruins changed my vision on music. Before them I never liked much really hard edged music.
Magaibutsu Lim.
Ruins :1986-1992 (JAP,1992)**
Tzadik

Ruins: Hydromastgroningem (JAP,1995)**°°°
Tzadik

Ruins :Symphonica (JAP,1998)***°
Magaibutsu Lim.
Ruins:Tzomvorgha (JAP,2002)****°
Simon Steensland :
OK Composed music in direction of Rock In Opposition
APM
Simon Steensland : The Zombie Hunter (1995)*
Spiral Architekt :
I read this was defined as "technical metal". There's much potential for heavy compositions, starting from art-progrock with metal hardness attitide. Only the group Aghora sounded a bit in the same direction to me. I'm not sure if the group is listed well here, but I noticed at least some intentions for more driven compositions.
U Totem :
Cuneiform Records
U Totem (1990)***°
Some avant gardistic elements in this, and Henry Cow influences or early Present, a RIO project with some brilliant moments. Interesting music but not easy going.
Univers Zero :
Belgian pioneers of this genre of "Chamber Rock Music", in Belgium still underestimated, even when they created this new sound, like Magma already in the 70's, 20 years before it became somewhat popular amongst some circles. "Heresie" is the darkest work (and still not in my collection)
Cuneiform Records
Univers Zero : 1313 (B,1977)****°
Cuneiform Records
Univers Zero : Ceux du Dehors(B,1981) ****°
Cuneiform Records
Univers Zero : Heresie (?) (Picture of Univers Zero during this session).
Cuneiform Records
Univers Zero : Heatwave (B,1986) ****°
Cuneiform Records
Univers Zero :Uzed (B,1988) ****°
Cuneiform Records
Univers Zero : The Hard Quest (B,1999) ***
Cuneiform Records
Univers Zero: Rhythmix (B,2002)***
Cuneiform Records
Univers Zero :Crawling Wind (B,1983)**°
Cuneiform Records
Univers Zero : Implosion (B,2004)***
Volapük :
Another example somewhat definiable as Chamber Rock Music.
Cuneiform Records
Volapük : Volapük (F,2000) ***
Zapotec :
was described at Laser's Edge as "a more improvisational Ozon Quartet". It is heavy/moody instrumental music with structured improvisation with drums, electric bass, electric guitar, violin. There are heavy rock elements as well as jazz rock touches. One of the more heavy lgroups, not for beginners.
Private
Zapotec Note of Sound Mind (F,1995 ):**°
Zypressen :
Japanese Classical chamber (rock) orchestra ; almost pure classical, (so more into the direction as Julverne, but more powerful and clearly composed), very refined.
Belle Antique
Zypressen (1996) ****