i think you are better off looking for an earlier audio research such as the sp 10. yes i know it is a full function preamp. also consider one of the earlier sp3 models. i think the newer models do not have the signature of tubes. perhaps, you can get lucky by finding some nos tubes with the ls5.
The best sounding Audio Research Line Stage preamp
I'm in the market for a used Audio Research Line Stage preamp and was wondering if anybody with experience on the following models could help me as to which you might feel would be the best sounding model. I'm after the ARC brand due to it's noted dynamics and clarity. It will be hooked up to a Classe CA-301 power amp and a pair of Magnepan's 3.6R speakers. These are the models I'm considering. The LS2B MkII, LS3B, LS5 MkII, LS12, LS16 MkII, LS22, and the LS25MkII. Thank you for all your help.