Hi: There has been much discussed on this subject previously. Searching the archives will bring a wealth of information. One of the very best can be found here:
http://forum.audiogon.com/cgi-bin/fr.pl?ddgtl&1051384332&openusid&zzBuscis2&4&5#Buscis2
http://forum.audiogon.com/cgi-bin/fr.pl?ddgtl&1051384332&openusid&zzBuscis2&4&5#Buscis2