Alsa buffer_size without dmix?

[Sven-Hendrik Haase <sh@xxxxxxxxxxxxx>]

Hello everypony,

I want to increase my default alsa buffer_size of 8192 to 32768 because 
I'm sometimes getting small skips in my audio. Now, usually people use 
dmix for this. I'm using the upmix plugin, however, to listen to stereo 
music on my 7.1 system.

Could any alsa wizards share the wisdom on how to increase the 
buffer_size without dmix or how to chain dmix into this?

My also asound.conf:

pcm.upmix71 {
    type upmix
    slave.pcm "surround71"
    channels 8
}
pcm.!default "plug:upmix71"


Now, I tried something along these lines:

pcm.upmix71 {
    type upmix
    slave.pcm "buffer"
    channels 8
}

pcm.buffer {
    type dmix
    slave {
        pcm "surround71"
        period_time 0
        buffer_time 0
        period_size 2028
        buffer_size 32768
    }
}
pcm.!default "plug:upmix71"

but apparently I don't grok alsa configuration syntax. It doesn't help 
that alsa-project.org is down (which is why I'm posting here rather than 
on their mailing list). I don't even need dmix itself, I just want to 
increase the buffer size but apparently dmix is the only plugin capable 
of doing just that.

Help appreciated.

-- Sven-Hendrik