Yes, any number of channels is possible. There are some (good)
soundcards with true multi-channel drivers (some supporting up to 16
channels in one device); information is on my Soundcard Attrition Page
(URL below). With such a card, under Windows, you can play the file
using Media Player. Csound would be able to play a quad (or 8-channel..)
file similarly. The crucial factor is that the card provides ONE device
supporting four or more channels.  The out-and-out leader on other
platforms is the Sonorus STUDI/O, for which drivers are (I think)
already available for Linux, and I know they are being prepared for BeOS
too.

For wav files, the new story is the development of
WAVE_FORMAT_EXTENSIBLE, which is expressly designed to support
multi-channel audio, including height, using defined speaker positions.
I have information on this on my website, with a couple of examples.
This is the new native format for Windows2000 and Windows98 Second
edition. 



Sergey Batov wrote:
> 
> Excuse me, seems it discussed in List already,
> but may be it will be not too difficult for somebody
> to write me again about soundcards and programs
> (especially) which support 4 channels wav file?
> And what about a number of channels > 4?
> Is it possible in wav-format?
> 
> Thanks in advance,
> 
> Sergey Batov   batov@glasnet.ru

-- 
Test your DAW with my Soundcard Attrition Page!
http://wkweb5.cableinet.co.uk/rwd (LU: 23rd August 1999)