Some of the current last.fm tracks are lo-fi renderings which don't have the original SID left. To find my surviving SIDs in the High Voltage SID Collection, search for "Teemu Mäki" at http://www.c64.org/sidfind/index.php . The publicly released SIDs are also available as MP3s recorded on real SID hardware as part of the SOASC= project.