ARC LS 16 MK1 vs. ARC LS25 MKll

I had been using an SP-9 MK II for about ten years. A few months back I tried an LS-16 MK II. It was an improvement but not a very big one. Can't really say if it was the preamp or some other variable (room?) that kept me from hearing the massive improvement the dealer said I would hear but I wasn't impressed for $3500. About three weeks ago I spotted a great deal on a LS-25 MK II and went for it only because I knew I couldn't lose (unlike buying a new LS-16 MK II). Well the sound was kind of disappointing in the sense it really didn't sound any better than the LS-16. It does sound good but there may be something to what all these folks keep harping on about the LS-16/25 MK I and the LS-5 series. I was really looking for an LS-25 MK I but I've only seen one in the past six months, I think I understand why now! At this point I'd like to hear one in my system before making a judgement, but that won't happen unless the local Audio Research takes one in on trade. I can't spend that kind of money again for a while. My wife was understanding the first time ....