What goes down, must come back up?  A number of ambitious music companies are making that very case with huge investment rounds.  That club now includes Sonos, a networked stereo specialist that just secured $25 million in fresh financing.  The round comes courtesy of Index Ventures, whose partner Mike Volpi now assumes a seat on the Sonos board.

TechCrunch first tipped the round, and the company has confirmed the injection.  In a conversation with the Wall Street Journal, Sonos CEO John MacFarlane noted that the funds will be used to power expansions in both China and Japan, part of a growth-oriented (instead of product-oriented) phase.

On the product side, a one-room, $399 system is also boosting prospects, though higher, $1,000-plus systems are certainly available.  This is a Series C, and total funding has now ramped past $60 million since 2003.