One of my favorites with „less common" instruments is a disc with music by Cage and Frescobaldi, instruments being the accordion and the (alto and tenor) trombone (performers: Stefan Hussong and Mike Svoboda). - The only listening samples which I could find are at Amazon.de.

I don't know whether you consider clarinet, flute or harp as "less common", but here are some suggestions [because of the restriction concerning the numbers of posted images and videos I'll post only the CD covers if they are different from the YouTube video]:

Trios for clarinet, cello and piano, for example by Zemlinsky or Ireland:

first movement:

first movement:

Trios for violin, cello and harp, for example by Ibert and Renié:

 

continued:

Trios for flute, viola and harp, for example Debussy and Takemitsu:

Lucien Durosoir has composed some - rather short - chamber works, for example:
- Caprice (cello and harp)
- Berceuse (flute and piano)
- Incantation bouddhique (cor anglais and piano)
- Vitrail (viola and piano)

Incantation bouddhique

 

continued:

And of course Isang Yun with many compositions for various instruments, a few examples:
- Rencontre (clarinet, harp and cello)
- Concertino (accordion and string quartet)
- Duo (cello and harp)
- Intermezzo (cello and accordion)

Rencontre

Intermezzo

 

Malcolm Arnold's Grand Overture is like a little concerto for two vacuum cleaners

 

Strictly speaking, and I say this having seen Arnold conduct this masterpiece, it's one vacuum cleaner and a floor polisher. And three rifles.

 

I just borrowed this from the library on a whim because I though the instrumentation sounded interesting (four trumpets, two trombones, and a tuba):

I was not familiar with any of the actual pieces performed (which were all arrangements for this brass septet). I thought it was . . . a little polite, maybe? I was hoping for something a little brasher and "brassier" (if that makes any sense). But I do appreciate the change of pace from traditional classical music orchestrations, which can get a little tiring after a while.

 

Two disks came immediately to mind. The first has an almost orchestral sound, but the balalaikas offer a unique timbre that is quite fetching. Then there's something quite soothing about clarinet choirs. A very organ-like sound, very unified.

 

French composers seemed to have a taste for unusual configurations - Jacques Ibert has already been mentioned, and both Francis Poulenc and Albert Roussell can keep him company. For example:


Poulenc - sonata for horn, trumpet and trombone (1922 - rev 1945):
Roussel - trio for flute, viola and cello (1929):

 

As chance would have it, I have just acquired a CD of Bruch's Concerto for Clarinet and Viola. An unusual pairing, though maybe worthy of more consideration?

 

As chance would have it, I have just acquired a CD of Bruch's Concerto for Clarinet and Viola. An unusual pairing, though maybe worthy of more consideration?

It's not that unusual. There's even a wikipedia article on this.
https://en.wikipedia.org/wiki/Clarinet-viola-piano_trio
"This combination of instruments differs from the traditional piano trio instrumentation, i.e. piano, violin and violoncello, and from the clarinet-violin-piano trio and the clarinet-cello-piano trio by the fact that the viola and the clarinet share roughly the same range. The combination of viola and clarinet is thus distinguished by the timbre (tone quality or colour) of the instruments rather than register (high versus low ranges, like violin compared with cello).

Wolfgang Amadeus Mozart: Trio in E♭ major "Kegelstatt", K. 498 (1786)
Robert Schumann: Märchenerzählungen, Op. 132 (1853)
Carl Reinecke: Trio in A major, Op. 264 (c. 1903)
Max Bruch: 8 Stücke (8 pieces), Op. 83 (1910)
Johan Amberg: Fantasistykke (Fantasy Pieces), Op. 12 (1910)
Julius Röntgen: Trio in E♭ major (1921)
Leo Smit: Trio (1938)
Heinrich Kaspar Schmid: Trio, Op. 114 (1944)
Leslie Bassett: Trio (1953)
Gordon Jacob: Trio (1969)
Theodoros Karyotakis: Trio (1969)
Jean Françaix: Trio (1990)
John Woolrich: A Farewell (1992)
Nicolas Bacri: Trio "American Letters" (1994)
Milton Babbitt: Triad (1994)
Colin Matthews: Three Interludes (1994)
Richard Stoker: Terzetto, Op. 32 (1996)
Franklin Stover: Two Pieces (1996)
Elliott Schwartz: Vienna Dreams (1998)
Roger Smalley: Trio (1992-1999)
Thierry Escaich: "American Trio" (2002)
Jeffry Phillips Burns: Coast Clear (2005)
Kalevi Aho: Trio (2006)
Philippe Hersant: Six Bagatelles (2007)
Nigel Keay: Trio in Four Movements "Adagietto Antique" (2009)
Huw Watkins: Speak Seven Seas (2011)
Juan Maria Solare: Sale con fritas (2005-2012)
Seung Ha You: Trio "Réflexion sur la mort à Claus-Christian Schuster", Op. 2d (2011-2012)
György Kurtág: Trio "Hommage à Schumann"
Matthus: Wasserspiele
Brett Dean: Night Window
Rudolf Escher: Trio
Rina Furano: Trio No. 2 in G major
Howard J. Buss: Reverie (1992)
Alexandre Carlin : Trio (2013)"

 

How about this?

 

Beethoven also wrote in this instrumentation

"Beethoven scored the various numbers for an unusual assortment of instruments including two each of flute, clarinet, bassoon, four horns, timpani, harp, glass harmonica, and strings."

The weirdest instrumentation in Mozart by far in my opinion is Maurerische Trauermusik, which has 3 basset horns + contrabassoon in its instrumentation.

The only other composer I know who wrote in this grouping (not the exact number of instruments, but the combination, basset horn + contrabassoon) is Richard Strauss, in his Sonatine Fur Blaser

 

Stravinsky -- L'Histoire du soldat

 

I've only had a chance to go through the music in your first post, sonance (actually between movements of the Ibert), but I've really enjoyed it - exactly the sort of thing I was thinking about. All unfamiliar and outside my comfort zone and I enjoyed it all. I never thought of an accordion that way but it's amazing how well it works based on the samples I heard. I had a hard time following what the piano was doing in some places in the Zemlinsky, but it was very interesting. The Ireland was easier to follow and very nice. So far, I'm also enjoying the Ibert. Not sure if I prefer the Zemlinsky or Ireland (though the Ibert has an unfair advantage with the harp) but the tones and colors are great. Thanks for those links and I can't wait to explore the rest of your selections and all the others.

 

Thanks to all of you for the wonderful suggestions and I hope they keep coming. I think I've played some or all of all the selections now.

apricissimus, I know what you mean about the not-very-brassy brass. I found a Faure piece and it sounded sort of like subdued mariachi. It is interesting, though. The balalaikas, clarinet choirs, glass harmonicas and the rest were entertaining listening, too.

elgars ghost, are you a fan of the Poulenc and Roussel or were they just things you knew of that fit? My classical music listening pretty much comes to a crashing halt before WWI except for Holst's Planets, Respighi's Ancient Airs and Dances (etc.), and Warlock's Capriol Suite. (And not all those are the most modern pieces even so. ) But something about the Roussel (who I'm not even sure I'd heard of before) and, especially, the Poulenc really worked for me, at least so far. I played your excellent pieces which inspired me to hear more and think I might love Poulenc's Concert champêtre. Thanks for bringing those composers to my attention.

 

Thanks to all of you for the wonderful suggestions and I hope they keep coming. I think I've played some or all of all the selections now.

elgars ghost, are you a fan of the Poulenc and Roussel or were they just things you knew of that fit? My classical music listening pretty much comes to a crashing halt before WWI except for Holst's Planets, Respighi's Ancient Airs and Dances (etc.), and Warlock's Capriol Suite. (And not all those are the most modern pieces even so. ) But something about the Roussel (who I'm not even sure I'd heard of before) and, especially, the Poulenc really worked for me, at least so far. I played your excellent pieces which inspired me to hear more and think I might love Poulenc's Concert champêtre. Thanks for bringing those composers to my attention.

You are welcome. Overall I am more a fan of Poulenc than Roussel but I enjoy the chamber output of both. Of the two, I'd say Poulenc runs up and down the bittersweet scale more - some of the earlier works tend to be quite playful and the later ones more introverted, as he wrote some of them as dedications for deceased friends or contemporaries. Most are less than 20 minutes long so there is certainly no chance of overstaying their welcome, but Poulenc had a gift for packing a lot into works of relatively short duration. As you already like what you've heard then you should be in for a treat if you decide to investigate further.

Brilliant Classics re-released a three-disc Olympia set of Roussel's complete chamber works which I think might be the only way you can get them in one fell swoop. Brilliant also released a three-disc set of Poulenc's chamber works (including the ones for piano duet/two piano) which is convenient, but Naxos have to be considered as over the course of five discs they also included some vocal works/incidental music which used chamber forces. Hope this helps.

 

Well you did say chamber, I know, but this Schnittke masterpiece is not full orch and well worth a listen. Note how the great violist Bashmet is being challenged by the work

Hahn would have to cancel a lot of her commitments to make a success of this work.

 

And then there is the viola concerto from Allan Pettersson, A work I would love to see Hillary perform/record.

 

^^^ Paul: how do either of your posts relate in any way to what is being asked for in the OP? They are concertos for commonly used solo instruments (violin, viola) and orchestra. They ignore the OP, not only through not being chamber music (and Schnittke, by the way, wrote a lot of fine chamber music) but also by not being for unusual combinations of instruments. I do get that you are passionate about these two composers but there are plenty of places where you can post about that and, if your message doesn't fit any of them, you can always start a new thread.

By the way, I think many people here will be familiar with a lot of Schnittke. Many of them like a lot of his music but are also fairly clear where they place him in their personal feeling about how important he is to them. Fewer, perhaps, know Pettersson and I think you are already having an influence on encouraging some who don't to check him out. There has been a fair amount of Pettersson in the "what I'm listening to now" thread over the last week. You are being heard and there is no need to shoehorn your size 10 opinions into size 5 threads.

 

How about Olivier Messiaen's Quatuor pour la fin du Temps, scored for clarinet, violin, cello, and piano? Love it! (Don't seem to see a lot of mention of Messiaen around here...)

 

^Messiaen has his fans here. But you're right that for such a major composer he is a little neglected in discussions like this.

Webern wrote a quartet for piano, violin, clarinet, and saxophone.

 

Can't forget unforgettable Ravel: Introduction and Allegro--a truly beautiful piece of chamber music.....

 

I like what has been called a "Boulez ensemble,' with plucked strings (guitar, harp, pizz. vln), struck pitches (metallophone, piano, vibraphone, marimba, xylophone), sustained sounds (violin), breath-produced (soprano, flute); the sounds divided into categories according to their "envelope characteristics" (attack transient, sustain, etc.) influenced by his studies of sound and synthesis at IRCAM, and to get an exotic "Eastern" or Balinese sound. Think of Elvis Presley's "Jungle Room."
Takemitsu has used ensembles like this, and it might all be traced back ultimately to Messiaen (Seven Haikai).

 

Carl Orff's rarely performed "Catulli Carmina " (songs of Catullus ) should appeal to anyone who enjoys the far more famous Carmina Burana , but instead of using a regular orchestra , i calls for a very large and varied ensemble of percussion instruments and more than one piano .