I own an AU-111 which I have restored over last xmas break. I should probably update
my thread with details. I also own a few other Sansui (and other brand) tube amps like the AU-70, HF-V60, Q3535...
The AU-111 is a thing of beauty. It is, I think, the amp that start the Sansui 'black face' trend... someone please correct me if I'm wrong. The AU-70 which came before it has a silver face. Yet, the AU-111 does to me look unique to all other Sansui amps before and after. No doubts it is a holy grail in terms of Sansui aesthetics.
The AU-111 also has plenty of power, the same as a MC240, whereas the AU-70 and most of my other tube amps are lower in power. Whether or not power is important to you isn't clear to me as I don't know which speakers you are using. One thing the AU-111 will give you over the MC240 is features like tone-controls etc. The MC240 though is of course a series piece of kit and I would love to try one out; I think you find many will argue the MC240 is likely the technically superior amp (the power vs distortion specs on the McIntosh are slightly better), dismissing the asian amp from across the pacific, but those people have probably not man-handled an AU-111... the iron on the AU-111 is the biggest I have ever seen with a 6L6GC class amp. That said the MC240 weight about the same and no doubt the McIntosh setup is very very serious gear too and they have some unique circuitry as we know... but anyway, vintage hifi isn't about specs, it's about sound....
As for the sound, I haven't had an MC240 in my home but I have heard a mono-bridged pair played through some JBLs and it was too bright for me. Maybe that was the JBLs. The AU-111 on the other hand has tone-controls, 'loudness', and 'presence' (which works different to presence on some other amps so read manual carefully) so it can sound however, you want. With the tone controls flat, I would say the AU-111 is less bloated in the bass than the AU-777A or AU-70 (these two models sounds almost identical when rebuilt, and they have a bit of that typical early sansui transistor tone with heavy bass). I think the AU-111 is more neutral than the AU-70 and AU-777A across the board actually. The 'syrup' of the AU-777A (with it's slightly recessed booming bass and slightly recessed mids) is lesser in the AU-111 but hand-in-hand with that comes another level of clarity and 'tightness' that I feel takes the AU-111 to another level. Maybe it was 'burn-in' as I had just done a full restore, but I quickly became a big fan of the AU-111 for it's clarity and image.
I will do a proper A/B/C/D comparison of the AU-111 to some other amps shortly (need to sort out my amp selector box with some resistors to provide load for tube amps when they are switched-out of circuit) and report somewhere (maybe over in my
AU-777A vs all contenders thread which seems to be my usual place for rantings).
Is the AU-111 very good? Yes.
Is it the 'holy grail'? Well you know how it is with these things.... it's a very personal tone/flavour decision and one man's turd is another man's caviar (sorry to be vulgar, but people do have very strong feelings about similar sounding amps). What I can tell you before doing my more rigorous comparisons is that the AU-111 doesn't sound like it is from a different planet compared to the AU-70... it is very much a sibling. A more powerful and heavier sibling with a slightly different flavour.
The looks and build quality are really something unique though (seriously, the OPTs on the AU-111 are truly giant compared to the Sansui AU-70 (which already has OPTs slightly bigger than Dynaco ST-70). Back to the MC240... again I think it is personal taste. I'm sure the MC240 is a fine amp with stellar specs.... so it's just a matter of flavour IMO. I may argue that the AU-111 is a lot more unique though, in looks and maybe rarity? And, personally, I'm a big fan of tone controls etc. And I'm a fan of Sansui.
Now, the fact is that you can buy 4x AU-70s for the price of one AU-111. The AU-70 is I think the true bargain of the vintage hi-fi market. I should probably shut-up and stock-up on AU-70s before everyone figures it out. That said the AU-70 is a LOT more difficult to work on than the AU-111. The AU-111 is not very tidy underneath but it is a pleasure compared to the rats nest that is the AU-70! And, even at the present asking price of an AU-111, I know it seems like a lot in vintage hifi circles, but it seems still a great price to me when comparing to the stuff you can buy brand new at your local hifi shop in the same price range. Consider taking the wad of cash you could buy an AU-111 with...taking that down to a hifi shop and telling them that is your max budget; they might even look down at you and tell you that will only buy some mid-fi... whereas with the AU-111 you are getting enough amplifier that the monster comes with wheels installed at the factory (no joke!). So I think the AU-111, in material terms, is well worth the asking price when put in that light, but when you consider you can get something like an AU-70 or other great amps for a fraction of the price I think it becomes a personal choice.