My earlier test, used lossyWAV v1.3.0, this was the commandline and stats:
C:\Users\Public\Music\Test\lossyWAV>lossyWAV.exe PinkNoisePlusSine.wav -q X
lossyWAV 1.3.0, Copyright (C) 2007-2011 Nick Currie. Copyleft.
This is free software under the GNU GPLv3+ license; There is NO WARRANTY, to
the extent permitted by law. <http://www.gnu.org/licenses/> for details.
Filename : PinkNoisePlusSine.wav
File Info : 44.10kHz; 1 channel; 16 bit; 00:10.00, 0.841MiB
Results : 7.7320 bits; 12.39x; 00:00.80; [F]
Clipping : 0.0081 bits lost, 242 clips remaining.
Having suspected clipping, and knowing that 3 clips per block are allowed at Xtraportable, and either 1 or 0 clips per block at extreme (it's 1 clip at -q 7.0, 0 clips at -q 8.0, not sure about -q 7.5, but I suspect it allows 1 clip per block), I tried using the following (this time I happened to use 1.3.0k but without it's special new mode, so the same as 1.3.0 release):
C:\Users\Public\Music\Test\lossyWAV>lossyWAV.exe PinkNoisePlusSine.wav -q X --ma
xclips 1
lossyWAV 1.3.0k, Copyright (C) 2007-2013 Nick Currie. Copyleft.
This is free software under the GNU GPLv3+ license; There is NO WARRANTY, to
the extent permitted by law. <http://www.gnu.org/licenses/> for details.
Filename : PinkNoisePlusSine.wav
File Info : 44.10kHz; 1 channel; 16 bit; 00:10.00, 861.3kiB
Results : 7.6705 bits; 16.12x; 00:00.61; [F]
Clipping : 136 clips remaining.
At first I couldn't tell a night and day difference like before, though oddly guessed exactly wrong 5 times in a row. Then I could just about pick up a slight roughness in the pink noise on the lossyWAV version so I reset the ABX and I was then at p=0.055 (5.5% probability I was guessing in my chosen 10 trials). ABX log in CODEBOX below (again conducted with no ReplayGain, no DSP and my soundcard's analogue volume control. I don't have time to ABX with maxclips=0 or a higher quality setting today - I only did this because it's a quick check of my suspicion, but would like to see where maxclips needs to be to ensure that -standard is transparent with 'whatever you can throw at it', even insanely loud full-scale sinusoid in noise test signals like this. I can well imagine that a simple gain adjustment like --scale 0.95 or 0.98 (number is a guess) could render it transparent by removing the signal-dependency of the clipping on positive peaks.
The allowed clipping works rather well for real music where strings of even 2 or 3 consecutive samples at positive full scale aren't normally audible. It seems a shame to waste bits making standard work for test tones, unless we provide a -testtones switch that limits clipping more than usual. (Edit - actually, it might not be an awful lot of bits if clipping remains sporadic. Personally, I tend to encode most of my music with Album Gain applied anyhow as if it were mastered at a sensible level, so I wouldn't often get anywhere near full scale.)
foo_abx 1.3.4 report
foobar2000 v1.2.2
2013/03/10 17:19:12
File A: C:\Users\Public\Music\Test\lossyWAV\PinkNoisePlusSine.flac
File B: C:\Users\Public\Music\Test\lossyWAV\PinkNoisePlusSine_lw130k_Xtraportable_maxclips_1.wav
17:19:12 : Test started.
17:20:09 : 00/01 100.0%
17:20:27 : 00/02 100.0%
17:21:10 : 00/03 100.0%
17:21:27 : 00/04 100.0%
17:21:43 : 00/05 100.0%
17:22:41 : 01/06 98.4%
17:22:58 : 01/07 99.2%
17:23:09 : 02/08 96.5%
17:23:24 : 02/09 98.0%
17:23:49 : 03/10 94.5%
17:24:26 : Trial reset.
17:25:32 : 01/01 50.0%
17:26:04 : 02/02 25.0%
17:26:35 : 02/03 50.0%
17:27:30 : 03/04 31.3%
17:27:58 : 03/05 50.0%
17:28:08 : 04/06 34.4%
17:28:18 : 05/07 22.7%
17:28:58 : 06/08 14.5%
17:29:21 : 07/09 9.0%
17:29:43 : 08/10 5.5%
17:29:57 : Test finished.
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Total: 11/20 (41.2%)