Of course everybody will have an opinion, but for Classical & Jazz, where the best heavy bass isn't the top priority, I'd choose the Sennheiser.  If you can live with their open-back design letting out (and in) sound to the room, it will give you the best overall frequency balance thus the instruments will sound compared to each other as they do in real life.  I don't even use their most expensive models, the HD600 is fine by me.

For Classical & Jazz the AKG K701 is a real top choice! If you need more bass you should have a look at the AKG K712 pro.

You'll always make a good choice with an AKG, Sennheiser or Beyerdynamic headphone, especially as some models are meanwhile cheaper than B&O headphones and sound much better. I compared the H6 against a K701, K712 and the H6 has no chance. It does sound good, yes, but the AKG's are another level. As a B&O fan I keep the H6, too. ;-)

I own a pair of grado headphones....excellent

Which ones?

Is the build quality good?

regards 

Type p500 

They are made of wood.

As down on B&O as I have been lately, I can recommend the BeoPlay H6. My wife has a pair, and they are the most comfortable closed back headphones I've ever used, and sound very, very good. Hers are the original ones that some call bass shy, easily fixed with a touch of eq. I've not heard the 2nd generation ones though that allegedly have more bass, but I think they'd be worth a listen.