Looking to upgrade my AVR to something a bit more powerful.
...I’m not in any hurry.
My main goal is to have something musical.
Just wanted to do a couple of "reality checks"!
Point 1:
Unless your other speakers are pretty power hungry, 75 watts is more than ample for the Klipsch towers! That is the beauty of buying an efficient speaker.
So don't expect a little more power to bring any real benefit! (and the fact that you are crossing them to the VTF15h reduces your power needs even further)!
Point 2:
Do not look for your AVR to provide musical or non-musical!
You can argue that some of the differences in the pre-pro EQ controls may be better than others, but I suspect you have been reading some of the reviews where time is spent talking about one receiver being too analytical and another musical, etc. That is BS! Any major company (like Denon, Marantz, Yamaha, Onkyo, Integra, Pioneer, Sony etc.) will strive for (and readily accomplish) low levels of distortion. If a receiver imparted a "sound signature" on your music, that would essentially add distortion. I won't argue that it is impossible there might be some minuscule difference in sound between two AVR's that might be barely detectable under ideal conditions, but I will argue that it is a fool's errand to try to find the AVR that will improve the sound of your speakers.
Speakers are the component (aside from the acoustics of your room) that will dictate the sound you experience (assuming your AVR is not driven beyond its limits)!
The Klipsch RP-280f are efficient and very engaging speakers! Enjoy them, because they are "where the rubber meets the road"!
With that said, there is nothing wrong with using your headphone jack to RCA connection as long as you are running only 2 channels (and I'm of the camp that a higher quality 2.1 system is better than a 5.1 system for the same cost - until you are getting into higher dollar systems).
I don't commonly
recommend the headphone jack option because I believe you can run into gain structure issues - which will manifest as an annoying hum - it doesn't hurt to try and I assume you would have mentioned it if you were dealing with an offensive noise, so you are good on that count.
But if you do want to "modernize" with HDMI connections and streaming audio, that is fine, just don't expect the other benefits you mentioned (although the excitement of new gear may put you in an emotional state to convince yourself you just made a huge upgrade to your system's sound).
Sorry, this is turning into a bit of a ramble, but these are the things that come up with experience in this hobby!
One thing that may be the most compelling reason to change receivers is whether your 15 year old unit provides bass management! IOW, is there a place with it where you can define the crossover point between your speakers and subwoofer? Traditional stereo receivers and older AVR's send full range signals to both the speakers and the sub, while a newer AVR will allow you to choose a crossover point (like 80Hz) and the speakers will not get (much) signal below that, and the sub will not get (much) signal above that frequency. Essentially, the AVR manages the transition to ensure a smooth hand-off between the subs and speakers.
Of the options you have listed, the 5 year old Denon 3000 at $200 seems like a good deal! Just pay attention to the seller (and his home if that is where you meet) to gauge whether he is the kind of guy who keeps his stuff nice or "rides it hard and puts it up wet"!
HTH!