Re: I got the DVD\'s.
TJG, as Joe mentioned above, the reason for the lower sound on virtually all DVD players is the increased dynamic range. This means that the difference between the softest sounds and the loudest on DVD is much greater than on TV, and even that VHS tape. So, since dialogue and normal ambient sound is much closer to the low volume end, and very loud sounds are rare, the DVD output seems low compared to other things. If you turn up the volume so that the normal sound levels sound as loud on the DVD as with other inputs, when you get to a really loud passage in the DVD, if it has one, it will be louder than the loud passages from other sources. VHS is that way compared to TV too, just not nearly as much. TV audio is compressed to reduce the dynamic range. If you have digital cable, or sattelite, using that system's menu, check the audio settings. You will probably be able to choose between light, heavy, and no compression. Set it to heavy, and listen to the TV. Then set it to no compression, and listen to the TV. With no compression, the sound from the TV will be lower, on all but the loudest passages. The DVD has no compression for dynamic range, and so it is the same effect.
Hypatia, your problem with sound dropouts -- you should replay the same spot in the DVD where you heard the dropout, to see if you hear it again. If you don't, it was probably a malfunction of the player, perhaps a dirty lens. Yeah, I know it's new, but it can happen. If it happens again in the same spot, it is either a defect in the disc, or possibly your player has a problem reading that spot for some reason. If you could play it in another player, and it plays okay, it would most likely be a fault of the playback programming (firmware) of your player. Manufacturers do update their firmware if it has enough problems, and many do it for free, but it will usually require a trip to the shop. I found most of this info by reading Jim Taylor's DVD FAQ, link above.