Most forgiving high end speaker 10k-20k?

Based on owners comments through the years, and reputation, Harbeth M40 would likely fit the bill - the house sound is known to be forgiving. Of course you could achieve a similar result following Onhwy61 advice (admonition).

Ditto HArbeth M-40.1's. Retail @ $13K. Great speaker IME.

Zu Definition 4. Despite having even higher resolution than Definition 2, it makes even 1980s CDs more listenable than any speaker I've listened to so far. Yet exceptional recordings will be revealed for all they are worth. I didn't expect the boost in listenability of CD. $12,995/pr. now, direct, 60 days mbg. 101db/w/m efficiency but high power handling too. Usable with a very wide range of amplification.

Phil

Personally I find the source and amp to be more of a factor regarding good/bad recordings. My local dealer used to sell Sim Audio and to me it sounded extremely detailed. With great recordings it is fantastic but with poor recordings it brought out all recording flaws. I found myself listening to the equipment more than the music. Naim on the other hand had a better and more musical balance.

That being said my local dealer had these set up with a variety of Dynaudio speakers up to the C4's. It has to do with total system synergy. I believe you need to find the speakers you like the most and find the right electronics to match because in my opinion the speakers make for the greatest difference in sound characteristics.

To answer your question more directly, I'd suggest Vandersteen models 2 or 3, both are under $4k. I've auditioned dozens of speakers and out of all of them they were by far the easiest to listen to, pleasant, smooth, no hard edges.

Onhwy61 made many good points.