Amateur inherited an audio system...

Keep it.
The resale value will not do much in the way of buying you anything but a retail cheap-a$$ junkpile replacement, and a few bucks to spend on beer.
Keeping them on the other hand will give you YEARS of listening pleasure.
You do not need to do more than plug then together and enjoy!
All the stuff talked about on this site doesn't need to concern you if all you want is something nice to play tunes on.
They are nice for a pro or a beginner.
I say keep them and enjoy.

I'm with Elizabeth .. keep it. You've inherited a very nice and balanced system.

It is simply not true that only audiophiles can hear the difference. My wife is not interested in hifi at all, but she says that music sounds a lot nicer on my system, she's just not bothered about her music sounding nicer, if that makes sense. Similarly I can tell that plasma TVs look a lot better but it doesn't bother me to have a better picture.

Most of the non-audiophiles who sneer at expensive hifi have never heard a good system and do not have any idea what they might be missing, and whether they would truly appreciate it.

Since there's no hurry to do anything I would spend some time with it and decide for yourself whether you feel that music is a more enjoyable experience with the inherited system. If it is not then by all means sell it. I recommend selling it here on Agon as you'll generally get better prices (and experience) than on ebay.

In my opinion one of the most beguiling aspects of a quality hifi is that it can present a very broad soundstage of music, that does not sound like it is coming from the speakers. This is the start of the illusion of realism. The system you've inherited is capable of doing this, but speaker placement is critical, and the LS3/5s must be on good solid stands.

There's a very straighforward, but good discussion of speaker placement here:

http://www.cardas.com/content.php?area=insights&content_id=26&pagestring=Room+Setup

(www.cardas.com -> insights -> Room Setup if the link doesn't work).

Have fun. You might have discovered a new hobby.

Wow, thanks for all the advices so far. They are all thoughtful and detailed. I do have the stands for the speakers and I didn't use them, and the speakers are spaced pretty closed to all other components. Maybe that's why all the monster cables and wires are long, they're meant to be spaced out...

I would like to give the system a little time to try out, and see if they suit my needs. And if I caved into the peer pressure and sell them, Audiogon will be the place then. Thank you so much for helping an amateur out.

Dont listen to your girlfriend,she may be seeing dollar signs,for her to spend!Without regard to how much enjoyment you might get out of it,,,for years to come!That is,,,if you enjoy music!

You may as well hear the system for what it really is BEFORE you make any decision to sell it, and to do that you will need to have the system properly set up; otherwise you may well be making a decision to sell based on improper setup resulting in those components sounding far below their potential (and possibly not much better than a Bose system). If I were you, I would post your general location; I'm sure that there may well be a friendly, knowledgeable Audiogoner who would be more than happy to assist you in getting at least a semi decent setup of the system in your room so that you can fully appreciate what you may or may not be giving up.