The 009 certainly improves in some areas over the 007 like extended frequency extremes and soundstage. Its really difficult to describe verbally how the 007Mk1 compares to 009. Some say its a dark sounding headphone, personally I wouldn't describe it that way. Its more that it doesn't draw attention to itself with exaggerated bass or lit up treble. Its a very organic, natural and integrated sound, not the immediate wow factor but the more you listen the more you realise just how great a headphone it is IMHO.
Many thanks, you post has helped me quite a bit.
It is a nice position to have both the 007s and the 009s at home. I will have to trade in my 007s so the decision to do that will need to be thought through. My demo at David's is tomorrow, so as long as I don't drive him insane! I think I should come to a decision then. I agree, the 007 is a great headphone and also not a WOW as soon as you put it on. It reminds me of how I find the Audio Note DACs, at a demo they are nice but not jumping out at you. However, after living with them, I found I was listening to a LOT more music and forgetting the gear.
Stax for me really get to the heart of the music. I know some say they are 'cold' or 'not accurate' I don't find that,. but I do think they need smooth and possibly warm up stream gear to sing.
I call it system synergy for a better description, get is right and you are in heaven.
Don't you just love this hobby?