The LS-1 is the line stage of the SP9 MK ll, they typically sell for under $500.00 and have a 6DJ8/6922 tube. The LS3 is completely solid state and sells for a bit more, around $500.00 to $550.00 in single ended and $650.00 or so in the optional balanced configuration depending on age and color of faceplate. There were a small number made with remote controlled volume/mute and these will bring at least $100.00 more. The LS2 is an excellent hybrid preamp that listed for around $2500.00 and seems to have fallen to around $650.00 to $700.00 a good choice if you need balanced outs. The LS-7 is an all tube unit that typically sells for $650.00. Many are really partial to this preamp and it is only a smidge more expensive than the LS1/LS3 series, and it is newer as well. I hope that this helps. The LS22 is much more expensive and does not seem to find favor with ARC enthusiasts. The LS5MKll is fabulous, but over double the cost of the other preamps mentioned. If you have the scratch after today's stock market action, the LS5mkll would be nirvana.