I just don't agree with some of the sentiment expressed. Some people really have a stone in their shoe regarding Audio Research. I don't know if the LS28 is better than the REF 5SE. I would say no, until I heard them side to side.
Yes, Audio Research upgrades (SE) or replaces components all the time. so do most larger companies with R&D departments. I agree that companies do this for many reasons.
1. They have to stay above or competitive with other like companies.
2. They have to personnel and manpower to keep upgrading and producing new products.
Smaller companies simply can't afford to keep coming out with newer and better every four or five years. It simply isn't cost effective for them. Parts storage, maintenance of equipment, etc.
It is also very unfair to compare how one company operates vs another. Unless you know the ins and outs of each company, the corporate directives, directions, etc.
The real test is, are they producing very good to exceptional products? Yes or no? Were you happy with your equipment when you bought it?
There is no law that says companies can't keep innovating simply because you bought a product. so car companies are supposed to freeze innovation on cars simply because you bought a car from them?
Nope. Volvo used to be the only company I know of that keep a production line for a particular model for long periods of time without change. Even that doesn't happen anymore, because they have to complete with the nine million (exaggeration) other autos out there in that particular price point and class.
All I can say is that Audio Research makes quality equipment. And they are one of the very few manufacturers that I can think of (Atmosphere, Pass Labs, Naim, Martin Logan) that will still repair their older equipment.
That really says something about these manufacturers. That also means that they must have replacement parts available. That also says something.
Simple answer. You won't know if the LS28 is better than the REF 5SE (doubt it) unless you hear them side by side in the same system and changing nothing except the units.
enjoy