i tried lame 3.98b8 ,but it's --preset insane is not CBR 320k.

and what can i do to get the best quality.

Your right its not encoding in CBR, instead its using ABR. I tried the Rarewares build at --preset insane, it could be a bug. Or lame defs decided to use ABR, since there is a reported bug on CBR.

Anyway you can use "-b 320" or "--preset cbr 320" to encode at 320k CBR.

For "best quality" - I wonder if there's any listenable difference between "-b 320", "--preset insane", "-b 320 -q 0" and so on.

when I use -X 7 switch i enjoy the sound more. But I haven't ABX'd it so can say for certain that I find it better.

Thats nice for you. However, no one cares about that here, and its off-topic.

in fact ,--preset cbr 320 is still ABR.

For some reason that switch is also mapped to encode at ABR, instead of CBR. It should be really encoding as CBR, but its not. I know using -b 320 works, but I recken that this might be a bug.

Thanks for pointing this out. I don't know how and why preset INSANE wasn't a CBR preset anymore, but it should be working again now (in CVS).

Rarewares compiles updated.