New AT cartridge thoughts/question

Well it is AT after all. That is their sound. Something to keep in the back of your mind, you prefer a less tilted up sound. Me too. 

A good part of what you're hearing as extension is probably just the grain and glare of a new cartridge. This will be less, the sound will get more relaxed and natural with more hours. It is AT after all, so don't expect a miracle, but hopefully you will be surprised how much it smooths out with some hours on it.

Peter Ledermann (Soundsmith) has stated cartridge ‘burn-in’ is mostly a myth. What does happen is the stylus diamond tip adjusts itself for the first few hours. 

As MC stated, AT’s are fairly known for their ‘tilted up’ sound. Clear, detailed definition, all great, but they seem to like the high end. As good as their clarity and definition seems to be, I went in a different direction as it seemed a bit ‘too much of a good thing’ to me.

Some claim 50 hours, some say its a myth. I’ve certainly heard some fairly drastic changes in the first few hours with one cartridge I’ve owned with the bass filling out and the top end calming down, and hardly any from others. After 50 hours you can be fairly certain any change will be from wearing out rather than wearing in and I generally leave it that long after an initial setup before fine tuning. The fine line styli are a bit more sensitive to VTA and if the arm allows it and the sound is a bit toppy at the moment you could try adjusting it a bit down at the back but probably best to leave it a while and just play some records.

Thanks for the replies.  Listening today and definitely enjoying the more detailed sound.  Right now the 2011 Aqualung reissue sounding great.  If I get just a bit of calming after a while that would be fine.    

bkeske, How would a stylus "adjust itself." I could understand the suspension adjusting itself. Thing is why would this always make a cartridge sound better? Why not worse? 
Ledermann thinks "break in" is purely psychological. He avoids saying it directly for obvious political reasons. Since I have nothing to sell I don't have to be political. Human hearing is incapable of detecting slow relatively minor changes in sound. It can detect abrupt changes above a certain threshold. It is more likely that we just become use to the sound over time so it becomes our new reference. Have you ever switched back to an old piece of equipment and gone "YUK?" "How could I ever have listened to that and I use to think that sounded great." You had gotten use to it. 
On the other hand I can alter frequency response +- 1 db any which way anywhere between 20 Hz and 20 kHz and none of us would know it. 2 dB and I think most of us could identify the part of the spectrum that was being modified. 3 dB is unmistakable to anyone. 1 dB is a pretty big change but to hear it you would have to go to 2dB which is huge. I doubt anything "breaking in" would make a 2dB change in frequency response.