Now they want you to replace your radios.
The consumer electronics and broadcasting industries - the same types pushing us to replace our trusty analog TVs with whizz-bang digital sets before all broadcasts go digital in 2009 - are busy deploying a new radio technology called "HD Digital."
The cheapest new digital receiver will set you back at least a hundred bucks, and better ones go for $200 to $600. But they're more than worth it, advocates say.
"As far as radio broadcasting goes, I think this is the most significant advance since [Edwin] Armstrong invented FM in 1933," said Mike Starling, chief technical officer at National Public Radio. NPR stations such as Baltimore's WYPR are in the thick of it.
There are critics, of course.
"Between the high prices, poor listening options, homogenized content ... it looks like HD radio is a high-level corporate scam, a huge carney shill," said David Downs, a music critic writing last March in the San Francisco-area alternative weekly East Bay Express.
The truth likely lies somewhere in between.
First, you won't have to pitch your old radios. Unlike analog television broadcasts, analog radio broadcasts will continue indefinitely, even when they're simulcast in digital.
Second, digital radio does provide a marked improvement in sound quality - a cleaner, deeper, more textured sound.
And because digital broadcasts use the radio spectrum more efficiently, stations can add channels alongside their assigned frequencies. Listeners with digital radios simply tune in the primary channel, then turn the knob up a notch or two to find the digital-only broadcasts.
For broadcasters, it's like adding entirely new stations at little additional cost.
So far, 1,521 stations (of 13,000 nationally) have begun digital broadcasts - often with new digital channels. Many of these are robots, commercial-free for now, but also without live DJs. Unlike satellite radio, there are no monthly subscriptions. To listen, just buy a new radio.
CBS-owned WHFS 105.7 in Baltimore - a beloved alternative rock station of the 1980s before station sales and finances forced a format change - is once again airing nonstop, commercial-free "true alternative" music on its HD-2 channel.
"I love this. ... I think it's going to be fantastic," said Neci, the new channel's sole disk jockey and the "last jock standing" after 24 years at WHFS.
"Everybody else is gone," she said.
So, what is HD radio?
First, HD in the radio context does not stand for "high definition" or "hybrid digital" or anything else, said Vicki Stearn, a spokeswoman for Columbia-based iBiquity Digital Corp., which invented the technology and trademarked the term.
"The idea is to give the general public a sense that this is next-generation, digital technology for AM and FM broadcasting," Stearn said.
Broadcasters who jump on the HD radio bandwagon must pay iBiquity a licensing fee that starts at $10,000, plus a slice of their profits. IBiquity also collects $1 for every digital radio sold - a potential gold mine if the format succeeds.
Analog radio is to HD digital radio what vinyl records are to CDs, said iBiquity CEO Bob Struble. Because digital transmissions consist of packets of ones and zeros, he said, HD receivers can decode the real broadcast and ignore the hisses, fades and pops that occur when analog signals bounce off structures and terrain - known as "multipath" interference.
There is a downside. Although digital signals require only 1 percent of the broadcast power of analog radio, their range is shorter, and they don't penetrate buildings as well.
"If an analog signal might be received maybe 40 miles away on a full-service FM station, your digital signal range will probably be 25 to 30 miles," NPR's Starling said. Drive out of range and your HD reception doesn't fade, it just stops. "It's something we're working on," he added.
AM digital is even more problematic. There's more interference with adjacent stations, especially at night. In fact, until September, digital AM channels had to shut down after dark.
But there is even more potential, broadcasters say. They can add data streams to identify musician and song titles on radio displays, or map traffic information onto a car's navigation screen.
Baltimore-based Polk Audio is building $499 HD receivers with iTunes Tagging, which allow users to "tag" songs as they play, and download them to their iPods later.
NPR Labs is working on technologies to transmit radio reading services for the blind and captioning services for the deaf.
For now, HD digital listeners remain a tiny segment of the radio audience -a half-million or so receivers amid 750 million analog sets. Arbitron, the radio ratings service, won't report HD listenership until next spring.
But digital radios are now standard in BMW and Mini-Cooper cars, and dealer-installed options in 23 Ford, Lincoln and Mercury models for 2008. Radio stations provide free ad time for stores to promote HD radios sales.
Boosters say digital radio is available in all major cities and to 83 percent of the nation's population.
Broadcasters say they're trying to fill gaps in local programming. New HD-only channels nationally include classical, jazz, bluegrass, independent rock, gospel, "Radio for Women" and programming for gays and lesbians.
"As more and more people get radios, there will be a lot more synergy going back and forth. That's just blossoming right now," said iBiquity's Stearn.
In Baltimore, eight commercial stations currently offer 16 HD channels.
Clear Channel's country station in Baltimore, WPOC 93.1 FM, has added a format called "The Wolf" on its HD-2 channel. It's more aggressive than its parent, with new tunes from established artists like Rascal Flatts and Brad Paisley, and hot new artists such as Jason Aldean and Taylor Swift. It's also nonstop and commercial-free.
CBS has added five new HD channels on four stations it owns in Baltimore, from ESPN Radio to "Good Time Oldies" and Christian music.
The network's "adult contemporary" station, WLIF 101.9 FM, plans to add a digital channel soon.
"We're going to try to do a hip Vegas format, with Harry Connick, Tony Bennett, Sinatra - all those acts that don't get a lot of play," said Bob Phillips, senior vice president for CBS in Baltimore.
In Washington NPR member station WAMU 88.5 FM moved the last of its long-running Sunday night bluegrass programming to its new HD-2 channel last year.
In Baltimore, NPR member station WYPR 88.1 FM will go digital as soon as next month after using $375,000 in grants to add hardware for HD simulcasts and a power boost.
WYPR will add its first new HD channel early next year - carrying additional news and talk from NPR. Formats for two more HD channels are still in play.
"NPR has five different streams available," said Andy Bienstock, the station's program director. "One is classical, one is folk, one is electronica. There's a jazz stream and ... nontraditional rock music. We're going to take our time and see where we want to go."