If you want the tone/feel of dead roundwounds you should use dead roundwounds. No half-rounds will give you that. Different tone, different feel. Half-rounds are usually too stiff/inarticulate for my taste.
I totally understand what you're saying about new roundwounds. Most of them are too bright/clanky for my taste as well. But some roundwounds go dead a LOT faster than others, and GHS roundwounds tend to go dead faster than most. GHS Boomers don't need more than a couple of hours of playing to get rid of excessive clank/zing. After 2-3 weeks of regular playing they are quite "dead". I've never understood why Boomers are listed as brighter than Pressurewounds on the GHS website. This may be correct for the first couple of hours, but after 1-2 weeks of playing, Boomers will be darker/warmer sounding than Pressurewounds for the rest of their respective lives. Boomers are actually some of the warmest sounding strings you'll ever find, except seom types of flats, and they only need a couple of weeks to get there. Personally I think a broken-in set of Boomers is even darker than GHS Brite Flats (which aren't really flats at all but half-rounds/groundwounds).
GHS Balanced Nickels are even warmer sounding than Boomer and also go dead relatively fast. My problem with Balanced Nickels is that they reach a point where they are TOO dead. With most roundwounds, including Boomers, I don't feel the need to replace them for YEARS. I like the tone of "dead" roundwounds. But with GHS Balanced Nickels they reach a point where I need to replace them only after 2-3 months of regular playing. I also find them slightly too supple for my playing style. I like them for recording, where I tend to play more controlled. But for live shows, where I sometimes like to dig in harder, the tone kinda falls apart.
The BEST "dead" roundwound tone I've ever gotten is with Pyramid Pure Nickels but these will need a couple of months of regular playing before they mellow out properly. Once they're broken in they have the warmest, fattest roundwound tone I've ever heard. They just need a bit of time to get there.
But most roundwounds can give you a nice "dead" roundwound tone if you give them enough time. Just avoid D'Addarios as their bright/clanky signature tone (even their flats!) means they will need a lot more time to "go dead" than many other strings. For many players this will be an advantage, but if you want "dead" roundwouds D'Addarios are one of the worst choices you could make IMO. I would avoid Slinkys as well. They mellow out slightly faster than D'Addarios but I don't like the tone of dead Slinkys. They just go DEAD, in a really bad way IMO.
