Veerapaneni ...
I've always considered that easy to drive speakers are the way to go. I'm presently using a pair of Legacy Signature III's ... 93db. The REF-75SE just coasts driving these speakers. In fact, the meters hardly move no matter what I'm playing. Also, I've found that many times, the lower powered amps in a product line can sound better than the higher powered spread. Not that I've always had easy to drive speakers. My old Accustat IV's come to mind. Great speaker, very musical ... but man 'O man what power hungry beasts they were.
I DO love the REF-250's, having heard them driving the Vandersteen 7's in the Optimal Enchantment room three years ago at the Newport show. All things considered, that was one of the very finest systems I've ever heard.
On expecting new gear to sound better than gear it replaces ... I remember when I first got my ARC REF-3. It replaced an ARC SP-14, a very nice preamp in its own right. I was a bit put off because while the REF-3 was better, it was just marginally better new out of the box. With the caps and tubes broken in ... the REF-3 just destroyed the SP-14. Same thing when going from my old, trusty, ARC-Classic 60 to the original REF-75. I love the Classic 60 ... now being used as a spare and soon to be sold ... but as the REF-75 began to break in, it was no contest. And then of course, the new SE versions are in another league all together.
Another benefit to the lower powered tube amps is the reduction in heat output. Southern California summers are HOT! Even today, this late in the year, our outside temps hit 100 degrees. The big amps would be out of the question in my room. I'm one who believes in turning off all electrical devises when listening to the system, and that includes the air conditioning.
Please don't take any of my comments as criticism in any way ... its just conversation between one ARC fan and another.
Take care ....