So it would take all of Google's cash on hand to buy 1 player (assuming they could even pull it off). It isn't like google's market cap is something they can liquidate or even really make any significant usage of.

Sony bought out their equal partners, Bertelsmann, for 900MM. [1]. That puts Sony Music's valuation at $1.8B in 2008. Global spending on music seems to be around $26B.[2] Although it's difficult to project a valuation from that, it's not unreasonable to assume that any of the tech giants could afford to buy a significant chunk of the industry.

[1]http://articles.latimes.com/2008/oct/14/business/fi-sony14

[2]http://mashable.com/2007/11/14/music-industry-decline/

If you want Sony Music you wouldn't buy all of Sony. Of course, these conglomerates may not be willing to sell off their "money-losing" record labels.

Definitely not Sony. How would they find artists to put onto minidisc/atrac/doomed-technology-de-la-décennie?

That'd be to buy ALL of Sony. Sony Music, Sony Pictures, Sony Computer Entertainment (which is mostly Playstation), and a not entirely incidental consumer electronics business. Sony might be worth more if you buy it and break it up, but this is exceedingly unlikely for a variety of reasons.

outright purchase is much less important than who can win a long legal battle. Don't sue someone who has more cash on hand than your net worth. it's dumb, especially when there's a lot of gray area around what specific license is on a particular song.