OK so I have only about 125 hours on the unit and it is breaking in. Dan suggests anout 400 hours. I find it to be a the opposite side of the spectrum from the SP8. Now Audio Research was never considered to be "warm sounding" say as the CJ's, but the LS100 is very close to a SS sound. It isn't meant to be an unsult as there are some great SS units out there. It's just that I wanted to get a tube pre for that warmth. Now I would say this is a nuetral pre and very revealing. Some recordings sound excellent others not so much. I have the suggestions on the tubes and will purchase some. Communication with Dan has been excellent and I am hopeful I will fall in love with the unit when fully broken in and tubed properly. BTW, I thought the review by Larry Cox on Positive Feedback Online was very accurate.
PS My SP8 is a "super" SP8 in that it was a special version from the factory with Wonder Caps and polystyrene caps. I spoke to Calvin @ AR and he said they had so many versions they stopped keeping track but he said mine was one of the better flavors.