Well I have the KG4 (stock no upgrades... yet), KG 5.5 (stock), HPM 100’s, ads L-1590 and 1090. Of those I believe ads do everything very well... however, I have SS and tube. I have an HH Scott LK-72 and it sounds unreal on both Klipsch.. upgrade from there??? Maybe Cornwall’s, Forte, Chorus??? But that would kick you out of the ball park of $500. The ads L1090 is an amazing speaker under the radar.. sorta. Underrated maybe. Balanced and amazing, but do not come up often. So... ads 810’s. Have a buddy that has a pair. Wow... wow. Some would say they lack bass but I like tight bass and not floppy bass or boomy. If you want more boomy bass maybe HPM 60. Oh, have those too. But the 60’s are not an upgrade from KG4. Listen, I have no complaints about the KG4’s. Not great at bass but I use a powered sub and fills the crossover point.
Man, I don’t think I have helped you!! Hahaha.
If you are patient, and looking for a steal, and want an ultimate upgrade IMO... look for ads L-1290. Man, they are wonderful and sometimes... I mean, maybe if you are lucky, you can grab some for 500.
Ads for me is the best all around speaker for everything from SS to tube, rock to jazz, and everything in between.
Again, just my opinion here based on what I have heard.
If you ever had the feeling of going tube, DO NOT get rid of those KG4’s. They are magic on them and I haven’t even done the mod’s yet.
Good luck man!!
Oh, by the way... the ads L-1590 are absolute crushers of detail, imagery, and projection. For me they top my list of owned speakers. Simply stunning sound. They will work with low watt but really need that big watt SS to open up and blow your mind. And they do, omg... do they ever.
I waited 6 years to find a pair and got them for $800 about a year ago. Perfect condition. So ya, if you are patient deals are out there.
a/d/s is my vote.