let's separate the two situations.

1. head to head at the dealer's showroom:
i have to view this dealer's accommodation realistically. bear with me. say i am the dealer. i'm there to sell anthems, not to see if a competitor sounds as good or better. i just might connect black to red and red to black and compensate for that in the anthem's setup menu so that ANY other pre in the same system would sound flat. given that, i don't think you should give much thought to the "shootout". psklenar's post is more viable.

2. at home: i agree with will 100%. there are many reasons why a quarter century old integrated amp is no comparison to the 950/770, much less better in any way...period. past break-in, if there is such a thing, no electronic equipment gets better with age.

you mentioned 2 jbl s312s. what are the other speakers in your system?
you mentioned the denon cd player. what dvd player do you have?
i have to say this...i don't listen to cds. it's a terrible format that is long overdue to be replaced. if i mainly listened to cds, i would not have bought a 950 prepro. so, i can't help much in that area, regarding the 950 vs. anything else. i regard soundhound to be the go-to guy there (read his post above). i know eq is a dirty word to cd purist fans, but maybe it would help you acheive the sound you are used to hearing with cds. maybe sound hound can help here, too.

will also is correct about the revealing nature of the 950 possibly requiring some upgrade of cabling/power conditioning...and i definitely agree with the speaker placement comment. in 6 channel bypass with sacd multichannel, very seemingly small tweaks in my speaker placement/height made dramatic changes.

i say list all equipment and let us all suggest ac/cable/eq/system config tweaks, if you don't mind our ramblings. my opinion is, saving $2500 buys a lot of these upgrades and you'll buy them anyway eventually, regardless of what pre you end up with.