Many investors weren’t sure what they’d see after February when the streaming music company, eager to control its royalty costs, put a 40-hour-a-month cap on mobile listening. But they liked what they saw in the Q1 report out today, even though the net loss increased: Pandora‘s shares are up 9.3% in post-market trading. The company lost $28.6M in the quarter that ended in April, worse that last year’s $20.2M loss, on revenues of $125.5M, +55.4%. The revenue number beat expectations for $123.8M. And the net loss, at 10 cents per share not including one-time expenses, matched the consensus forecast. Total listener hours were up 35% to 4.2B and Pandora says that ad sales increased 49% to $105.1M. Much of the jump is due to mobile use: The company generated $23.23 in ad revenue for every 1,000 ad-supported listener hours, +29.9%. The metric shows $48.16 for listening at traditional computers, +3.5%. Pandora ended the quarter with 2.5M subscribers, +114% vs this time last year and up 700,000 over the three-month period. That’s more than it added in all of last year and gives Pandora “the largest U.S. streaming subscriber base of any music service,” CEO Joe Kennedy says. The revenue growth was somewhat offset by a 48.4% increase in content acquisition costs, to $82.9M.