Liberty Media CEO Greg Maffei paid Amazon a backhanded compliment today, telling analysts that he considers the e-retailer “a ridiculously scary company.”

Maffei made the characterization when asked about the threat Amazon’s streaming music efforts might pose to SiriusXM, which Liberty owns — along with a threat its new Prime Live Events concert and ticketing initiative could pose to Live Nation, in which Liberty owns a major stake.

Amazon “has an ability, because of its scale, to invest at incredibly low or negative rates of return — because they can cross-subsidize, and the market is willing to suspend disbelief in future profitability,” Maffei says. It’s also “dominated or controlled by a very smart, aggressive, long-term thinking CEO” in Jeff Bezos.

“That’s a scary, formidable combination.”

Even so, Maffei says that Live Nation is protected by its “promotion relationships, venue relationships, management relationships” while Sirius XM is distinguished by its “ease of use in the car” including exclusive deals with auto makers.

“Are all moats impenetrable? We’ll see,” the CEO says.

Maffei steered clear of new disclosures regarding Sirius XM’s interest in Pandora Media. The online music service’s shares have been whipsawed today following a weaker-than expected earnings report, along with reports that it’s looking to sell itself after private equity firm agreed to invest $150 million in the company.

“Nobody has offered us an investment opportunity,” Maffei says. “If somebody presented one, we’d look at that.”

Last year SiriusXM informally offered to pay about $3.4 billion, or $15 a share, for Pandora — which the board rejected. Today the shares trade for about $10.

Maffei says that Pandora “undermonetizes” its opportunity to compete against radio for ad dollars.

“It has a superior product to many of the other free services” due to its ability to geotarget listeners, he says.

Meanwhile, Maffei is upbeat about the new wireless phone alliance between Comcast and Charter Communications, which he calls “as natural as peanut butter and jelly.”

The No. 1 and 2 cable companies said yesterday that they will share information, and collaborate on negotiations with vendors and service providers, as they create services in their respective markets. Their wireless phone offerings will depend heavily on wifi, with cell phone connections provided on a wholesale basis by Verizon.

Comcast’s Xfinity Mobile will launch by the end of June; Charter is targeting 2018.

Working together will create “meaningful synergies, meaningful opportunities,” Maffei says.

Although there are “surely challenges around brand,” the collaboration gives the companies “an enormous amount of scale” and “sets the tone for other potential combinations and other potential opportunities to work together.”