could someone point me to the settings/string that will give the highest audio quality VBR?

Now thats a can of worms.....
wander over here 66.96.216.160/cgi-bin/YaBB.pl and also over to www.hydrogenaudio.org
But if you want to save some time try:

In reply to:

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VBR (Variable Bitrate) settings:
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Even Higher Quality

Higher Quality (Slower):
--alt-preset extreme
(bitrates 220-270 kbit/s -- usually averages around 256kbps)

Faster (Very Slightly Lower Quality):
--alt-preset fast extreme
(bitrates roughly the same as above)


Very High Quality

Higher Quality (Slower):
--alt-preset standard
(bitrates 180-220 kbit/s -- usually averages around 192 kbps)

Faster (Very Slightly Lower Quality):
--alt-preset fast standard
(bitrates roughly the same as above)

Compromising, a little bit lower quality than pure standard, but less bitrate (-Y: usually limited up to 16 kHz) :

--alt-preset standard -Y

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Personally I am using "--alt-preset fast standard".
Be warned, however, this setting are pretty CPU intensive and therefore it takes quite a while to encode.