And is a Piano Trio more rewarding for its players than an audience?

I suppose that depends on the players and upon the audience.

As it is, I find playing in a trio much harder than playing in a quartet.  Balancing the voices when they have such different characteristics is very hard, wheras in an all string ensemble you can (relatively) easily achieve the same shape to each sound.

But then again, I think that may be why Piano Trios may give String Quartets a run for their money.  String Quartets have 'just' a stringy sound, whereas Piano Trios can go beyond this.

I'm not sure about other chamber combinations.  Wind groups somehow don't have the intimacy of SQs or PTs, but I am sure some members will provide counter examples to correct me.  Mixed groups can work well, but they aren't exactly widespread.....

Tommo

JS Bach was as we all know a master of instrumental colour as well as of everything else he turned his attention to, a fact from which none of his arrangements/reconceptions between media can detract, and which is particularly in evidence in the careful and often unusual choice of instrumentation in such works as the "Brandenburg" Concertos, the cantatas and the larger-scale works for the church. Most of the Kunst der Fuge on the other hand can be played very successfully as string quartet music, and I prefer to hear it that way than on a keyboard instrument.

All other things being equal (which they never are), I prefer the sound of a string quartet to that of a piano trio. Neither has the latter really had its Arditti or Kronos to bring its repertoire up to date, which is a shame.

"Mixed" chamber music groups are much more widespread now than they were a hundred years ago, with the Pierrot lunaire combination (piano trio plus flute and clarinet) probably generating more repertoire than the wind quintet these days, and the "Sinfonietta" (five woodwinds, four brass, percussion, piano and string quintet) even more than this.

... although I would see that "homogeneity" more as a bug than as a feature, ie. something which might require creative workarounds in order that the music not be enslaved to the traditional characteristics of its instrumentation. And this isn't the only problem: the layout of the quartet implies harmonic voicings inherited from tonal music (smaller intervals at the top, wide spacing between "tenor" and "bass").

Richard, was it not Pierre Boulez who exposed timbre as a 20th century invention? Was it perhaps in 1908 it first raised it's ugly head

Who could?

Rachmaninoff knew what Stravinsky and other were writing. He did not feel that he can write this kind of music. He remained true to himself.

It is not easy to be true to yourself, I suppose.

I love piano trios. Some times I love them more than quartet. I get tired of string sound. Piano brings new colour.

I wish composers will not forget piano trios. Please.

I don't know Boris Tchaikovsky quartets. Of course every one has his own taste, but I love Prokofiev's music. I love him as much as I love Stravinsky. For piano Prokofiev wrote very good music. I don't think I would want to be without this repertoire.

Four woodwinds, three brass, surely? I'm off-topic (but the rest of this post isn't!).

I was about to mention Ferneyhough apropos string trios before TF did. Ferneyhough's programme note, as I recall from hearing an early performance of that piece at the ISCM in Manchester in 1998 (can it really be so long ago?!), drew attention rather interestingly to the fact that, having fewer definite generic associations developed in the Classical period and its aftermath than does the string quartet, the string trio could be regarded as a sort of hybrid genre with elements of the viol consort and of various other histories informing it. This would have been in the period when he was very preoccupied with baroque-type structures (cf. trio sonatas) with pairs of movements slow-fast, as in Kurze Schatten II etc., although IIRC the Trio is more through-composed or rather cross-cut between types of material.