This CD is absolutely top-notch. If you're a fan of Gershwin, you'd do yourself a grand favor by buying this collection. The technically immaculate yet stylish performance of Rhapsody in Blue, per William Tritt, is alone worth checking out the collection (it's my personal favorite rendition of the Rhapsody); even so, every other piece in the collection is of equal quality, and I can't recommend these CDs enough.
As for the volume levels, I've had no problems with the volume being unusually low, and I've played this collection on pretty much every piece of musical equipment I own (MP3 player, 3 computers, 2 portable CD players, Xbox 360, home theater system).