on ADPCM

From jhl: ADPCM is mathematically lossy PCM based on a fixed compression ratio which works by storing the diffence between samples. MS Says its ADPCM only works on stereo, 16bit stereo files, and compresses downto 4-bit ADPCM. I expect apple's IMA4:1 to be similar. Both "new" and "old" files have the same codec so I don't know what you're talking about. Apparently very low frequencies don't get represented well in ADPCM, but the audiable difference should be unnoticeable when decompressed to 16bit. The only way you can tell is if you use a cumulative FFT on original PCM vs ADPCM.

About 32bit, your DAW is importing the ADPCM as 32bit. It's not worth anything more than 16bit, and i checked with Ozone 4's bit meter: only the top 16 bits light up.

About Love song: seems to have noticeable amounts of distortion in the lead vocals.aif. I beleive this isn't caused by ADPCM, but caused by bad mastering/transfer from originals.