[sigh]
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First I convert flac to wav with dBPowerAmp. Then I'm going to use EAC to convert to mp3.
Why two steps? Do it in one; anything else is a waste of time.
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I'm thinking to use this one:
-b 32 -m j -h -V 0 -B 320 --lowpass 20 -q 0 --vbr-new
Really?
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Is this command line have something wrong?
Almost everything.
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Lame documentation says that option -h do some quality improvements and behaves the same as the -q2 switch. So if I want to use -q0 I don't need to use -h?
No, and -q0 has no effect in VBR mode, anyway.
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Another question about -m option. Which stereo mode has better quality stero or joint stereo?
-m j is default (and thus redundant), and superior.
Did you do the most cursory research for yourself before posting this? I hope I don't have to direct you to Google, or even Hydrogenaudio's own wiki (which I'm sure appears high in the former's results).
As stated above, for 'maximum quality' (i.e. minimum likelihood of audible differences from the source file), use -b 320. For 'maximum quality' VBR (which will generally be just as reliable, while not wasting 320 kbps frames on simpler audio), use -V 0. That's it; no -q, no -m, -b, -B or anything else.