Verified answer

A lot of orchestras will come out with a 'pops' album, that will sometimes include remakes of contemporary hits.

Aside from that, just search "Vitamin String Quartet" or "String Quartet tribute to" in Amazon.com, and you'll get a list of dozens of albums (Metallica, Queen, Evanescence, Nirvana, etc.) You're already on the right track. Unfortunately, I don't know of any other orchestras/groups that focus solely on contemporary remakes.

I have a slightly different take on this subject. The term "Classic" or "Classical" in reference to music may be a bit overused. It has been applied to denote various genre of other types of music, including Country, Rock and Jazz. I think of it as applying to music that is of a vintage and style marked by excellence. Many classical composers created their music long after Beethoven, Bach, or the other composers generally regarded as classical. For example, an American composer whose work has been considered classical is Gershwin, who composed mainly in the first half of the 20th Century. An alternative term I like is "Great Music." The problem is that almost any term we use can be stretched or shrunk according to a person's tastes. I think we have to categorize music--I don't know any other way to classify it--but bear in mind that the eye (or ear) of the beholder may have a lot to do with how the categories are perceived. We might well do better to sort music out by categories such as opera and symphonic, but I would think this would create a risk of excluding some very worthwhile music. An interesting question. I'll be thinking about it for a while.

Me thinks yeer in the wrong category, ma dear.

Alberich

The London Philharmonic does a lot of what they call "pops."