Mark Levinson 27.5 versus modern day amps

That is a very respectful comment for the 27.5. Which Soulution amp did you compare it against? 

Testpilot I think the US market has gravitated to smaller one box solutions in recent years as real estate has skyrocketed resulting in audiophiles in crowded or expensive locations to downsize. They do not want to have larger and heavy components taking up space.  Class D has come a long way but I still don't think it has reached transistor based SS sound quality.  Just my opinion :)

The US still has the largest average living space compared to the rest of the world (perhaps Australia is larger, but the point is the same)

That may be true but I am referring to crowded high priced areas such as San Francisco, New York, etc...Smaller living spaces that people don't want bigger gear stuffed in tight spaces. My main point of reference is someone who lives in the Bay area and has been an audiophile for years with tons of friends who have downsized.  Hey more muscle amps on the market for us haha :)

Any user comments on 331 vs 27.5?

I know this is a very old thread, but wanted to add my comments. I recently purchased a pristine 27.5.  On consignment at a guitar store in a small town.  To be honest, bought it because it was a ML and the price was so low. Boy am I impressed.  The amp hits way above it pay grade. The current is amazing. Driving Aerial Acoustics 8B's, which should have 200 a channel. The 27.5 handles them in spades.  Watts vs current really do seem to be like torque vs HP. 

Have used it both with a recapped/updated SF Line 2 PRE and with a Levinson 38.  Very different sound. Both very refined and enjoyable.