ATC or Audio Note (2-way)

Definitely ATС ... model 50 - will sound great in a home system (nothing needs to be redone).
AN - it makes no sense to buy ... if level 5 with their amplifier can be made to sound (thick fat type of music), then the initial levels are quite weak ...

jjss49 is right. As an Irishman might say, thery're as different as chalk and cheese.

Sorry, no experience with Audio Note. I’ve owned two different models of ATC’s, including the ATC SCM 19’s. Maybe they are not the VERY best in resolution available, but I can assure you that there is no way that they could be modified to be "much higher" in resolution. There simply isn’t enough room in the scale of resolution above the ATC’s for there to be enough of a delta to be called "much".

~Oran

Very different? I've heard ATC but not AN. (I've used a lot of AN components in various DIY, though).

Thought both were very mid-centric?

I’ve heard both. It doesn’t seem likely you’ll get much more resolution by tinkering with the ATC and you’ll possibly compromise its sonic balance (btw most ATCs bar the big ones are bass-shy). Modding the AN will probably modify its sound -- but do you really want that? These are not exactly cheapo speakers.

I would suggest another diy challenge: purchase vintage japanese speakers and mod them to approach contemporary performance standards!