Well, I'm going to be the guy that chimes in with the opinion that nobody likes.
First, if your speakers do jazz real well, but they suck for death metal, your speakers just suck. I'm not one of these guys that think there's a speaker for every type of music because there really are very well rounded speakers that do everything very well.
Second, I wouldn't suggest 901's to my ex-wife. I'm not a fan of jazz, but I appreciate that it's nuanced music. 901's are specifically designed to destroy sonic precision and nuance. If you're looking for that vastly spacious kind of sound try Quads, Maggies or ESS.
Third point. The 2270 has a warm sounding amp. Speakers on the brighter side compliment it well. Think Focal, Golden Ear, Paradigm, ESS, and MartinLogan.
I'd also recommend getting that 2270 serviced and/or recapped if it hasn't been already. It makes a difference and that's a unit known to drift from spec.
Like I said from the start, just one guy's opinion. Take it or leave it.