If you're looking for the one that has the best of the tube-like qualities, go with the LS5. The rest of them, save the 16 and the 25, are far more solid-state like in character. I personally think the LS5 is the best of the line stages ARC has ever put out, though that's my taste and may not be yours. I assume that you're using all balanced connections, though, snce that's what the LS5 uses.
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.