Dang - calm yourself. Night and day is a big difference and I agree entirely that people throw out the term 'NIGHT AND DAY' when what they really mean is 'SLIGHT IMPROVEMENT, BUT NOTICABLE'.
I had the opportunity to listed to Meridian's top of the line speakers A-B tested with B&W 801s. The Meridians sounded cleaner, but also cost about $80,000.00 more or something ridiculous like that. Not a LOT clearer, but noticably clearer.
This is what some people would call night and day.
On the other hand - what I would call night and day is the fact that almost every Yamaha, Denon, and Pioneer product I have worked with has been very reliable for users, while the Krell and Meridian equipment I have worked with has failed, locked up, seized up, and customer service has been MIA for those companies in dealing with their issues.
Night and day?
Well, compared to the sound quality of the $1,000 receiver vs. the $10,000+ receiver/amps, I would say that a complete product failure w/no support vs. day to day reliability IS night and day.
Everyone needs to put perspective on what they are comparing. A Yugo vs. a Honda Accord? Or a Honda Accord vs. a Toyota Camry? Which one is a 'night and day' comparison? One review would call the Accord phenomenal and worlds better... the other would call it very similar and not overly impressive.
Night and day indeed....
Get some humor and look for smilies - they mean something.