The sub is an old JBL (10+ years?), long discontinued. So what I’m hearing thus far is stay with one system, upgrade front L/R, sub and center, the Denon amp will work fine for both theater and music. And, how important is it that the front L/R and center brand of speaker match? The music by the way is a little “flat” sounding, could be the speakers. I also see Denon recommends the Auto EQ feature which I use so I am not controlling bass/treb/mids on my own - wonder if that is something to change too or if better speakers will just bring everything to life. Thanks for the input, expensive decisions.
Trying not to get off topic, but do you listen to music on Neural X, Dolby Sur, Multi Ch Stereo, 2 ch stereo, etc.? The Denon receiver provides all of these choices for music playback.