volt11: I tried a bunch of 5.1 surround sound discs out in the Volt tonight. Surprisingly, it apparently plays DVD-Audio discs in the DVD-A format. This is a much more advanced standard than dts or Dolby Digital, which also play (see below.) Not that it makes a big difference on the Volt audio system, which is good but not going to win any audiophile awards. As to whether or not they play in surround sound, I believe the answer is a qualified Yes. There is definitely an added sense of spaciousness, although sounds mixed 100% to the rear don't sound much like they come from behind. I think what's going on is that rear information is blended to the front channels about 50/50, while front only information stays mainly in the front. The Volt has no center channel, so center information seems to be split 50/50 between front right and front left, as expected.
Surround discs that are in DVD format do keep playing while on the move, but the video portion is blanked out. Tracks can still be skipped with the normal controls. For folks who are not familiar with music (not movie) surround sound discs, there are a few basic types and here's a little primer:
dts on CD (plays in Volt: YES): dts is a data-compressed format often used for movie soundtracks and competes with Dolby Digital. Standard dts (I won't go into the newer BluRay formats) is generally higher quality than Dolby Digital, which uses more compression; because dts data is compressed, 5 discrete channels plus 1 subwoofer channel (5.1) can be squeezed onto an ordinary CD, where a CD can only hold about 0.7 GB compared to DVD's up to 9.4 GB. Two of the better examples IMO of this type of disc are Alan Parsons / On Air http://tinyurl.com/4jsd6dd and Sting / Nothing Like the Sun http://tinyurl.com/4paboou (note how the prices of some of these discs have risen dramatically since going out of print.)
dts and/or Dolby Digital on DVD (plays in Volt: YES): Many surround releases appear in this format, which is produced just like a regular DVD. Usually there is a choice between dts and Dolby Digital surround soundtracks from a top level menu. The video portion of these discs is usually used to display lyrics and/or other album graphics. Examples include the 3 aforementioned Genesis box sets (covers every album they ever made, remastered in surround sound), and for a pretty impressive electronica experience (good demo disc), try Jeanne-Michel Jarre / Aero http://tinyurl.com/4zxdfgu.
DVD-Audio (plays in Volt: YES): One of 2 super high-fidelity formats introduced around 2000, DVD-Audio discs (aka DVD-A) allow the higher capacity of the DVD to really be exploited for audio, and works to address the complaints by many "golden ear" audiophiles that the CD (circa 1982) lacks some of the more musical qualities they attribute to vinyl (forget the fact that vinyl has some serious flaws of its own.) A typical DVD-A disc has 5 uncompressed channels at 96 KHz sampling rate and 24 bit sampling depth (plus subwoofer channel.) I know that's greek to most people, but compare those numbers to a CD which has 2 channels at 44.1 KHz sampling rate and 16 bit depth. Each channel alone of a DVD-A uses more than 3 times as many bits per second than CD, and it has those extra surround and subwoofer channels-- that's a lot of data! (stereo DVD-A can go up to 192 KHz sampling.) Those higher rates and bit-depths, on a very good system, translate into more silky high frequency sounds (such as symbols), punchier dynamics, and simply a greater sense of realism, space and detail. Technically, DVD-A discs can be played on any DVD player, however relatively few can play the actual super hi-fi DVD-A soundtrack (it appears to me that the Volt does.) Those players that can't (most of them) get alternate soundtracks for backward compatibility, in Dolby Digital and/or dts. There are lots of great DVD-A releases, but one I particularly recommend is The Beatles / Love http://tinyurl.com/47jm5kj, and it's also hard to go wrong with the classic Queen / A Night at the Opera http://tinyurl.com/4z47ukd.
SACD (plays in Volt: as regular 2-channel CD only): Super Audio CD (SACD) is that other super fidelity format, brought to market by Sony. It's really neither a CD nor a DVD, but like a DVD it has 2 readable layers and usually one of them makes it looks like a plain old standard CD to non-SACD players. I think Sony's hope was that this would allow it to be widely adopted by record labels, but in a world where the average consumer's playback standards were actually sinking (down to the now-ubiquitous MP3 or or AAC iTunes track, which use "lossy" compression and are inferior to even the old CD), neither of the competing SACD and DVD-A formats really made it into the mainstream. According to Wikipedia, SACD is still lingering for audiophile releases, but I wouldn't expect many rock/pop artists' new releases to appear on it any time soon. SACD uses a totally different, 1-bit delta encoding scheme, which makes it difficult to compare spec-wise to DVD-A, but in a nutshell they are practically interchangeable in terms of sonic goodness. As mentioned by chemdawg, Pink Floyd / Dark Side of the Moon is a great SACD release, and it's still downright cheap at http://tinyurl.com/6zfrftz.
If you want a great, highly regarded yet still affordable ($500) universal player for your home, I recommend the Oppo BDP-93 (http://www.oppodigital.com/blu-ray-bdp-93/), which also plays Blu-Ray video discs.