Mozart

[Spotted Horses]

Of course not. The title is a mystery to me as well.

Four orchestras is an obvious reference to the Notturno K286. Maybe they combined the forces of the two PI ensembles listed for a grand ensemble to perform the other two symphonies? We need someone who had the CD and can read the booklet for clues.

[Florestan]

Four orchestras is an obvious reference to the Notturno K286. Maybe they combined the forces of the two PI ensembles listened for a grand ensemble to perform the other two symphonies? We need someone who had the CD and can read the booklet for clues.

The most probable explanation is that the two orchestras were combined for S34 and S40 and split for KV 286. 

[Jo498]

I have that Brüggen disc. It's just a fairly big orchestra in the symphonies, including probably doubled winds in the tutti, put together from the two named ensembles for the symphonies.
So orchestra in the CD title is used ambiguously: 2 orchestras play music for 4 orchestras (and for only 1) 
There is actually no further information about the exact strength of the combined orchestra for the symphonies. Simply all members of both are named but I doubt that the doubled the timpani for K 338, so probably only one of them is playing.

There are a few "double orchestra" symphonies by JC Bach but I don't know how they are set up.

[Mandryka]

I think I prefer this chamber reduction of K364 to the original.

Does anyone know who wrote it? And when?

[Que]

I think I prefer this chamber reduction of K364 to the original.

Does anyone know who wrote it? And when?

It's beautiful!

I looked into this before: Anonymous transcription/arrangement c. 1807/8, published by Sigmund Anton Steiner of the Sinfonia Concertante K. 364

[Spotted Horses]

I think I prefer this chamber reduction of K364 to the original.

Does anyone know who wrote it? And when?

I was going to ask the same question. I have it in a box set with no documentation other than basic track information, but I found the back cover of the original release on Discogs and it says the arrangement is anonymous from 1807.

[Mandryka]

I was going to ask the same question. I have it in a box set with no documentation other than basic track information, but I found the back cover of the original release on Discogs and it says the arrangement is anonymous from 1807.

I just found the booklet -- it's quite informative. Here

https://ibb.co/mF9svhD2

It's a fabulous performance of a lovely piece of music.