I bought Inventions for Electric Guitar remastered and it was 99.9% exactly the same as the Spalax CD. Same levels, dynamic range, etc. If Manuel did remaster it he tweaked it so minimally I don't think anyone could tell the difference and I'm sure he used the Spalax CD as a source. I heard this was the same on some of the ART albums too.
If anyone has an ART remastered album that they think is significant different to the Spalax I'd like to try it.