Good advise so far. I'll add a few tips that will be critical due to your lack of feedback in selling gear. I don't know about other buyers but when I see a first time seller with super high end equipment I think "scam."
1. Take lots of pictures. Make sure you photograph each piece from every angle, even the bottom. Carefully photograph every scratch and flaw the best you can and document these in the sale description.
2. Note the serial number of each piece and photograph it. If someone is selling stolen gear they would never do that.
3. Document the history of each piece if you can. When was it purchased? Where bought? Did your dad keep the original sales receipt? If you can trace each component back to the original dealer (if bought new) this is a huge credibility factor.
4. The fact that you have original boxes is really important. I will pay 20% more for a piece in pristine condition if it has the original packaging. Take photos of the boxes and include them in your selling description.
5. The Revel speakers are very heavy (178 lbs) and expensive to ship (they have to ship LTL Freight). If your dad really kept the speaker crates that's a big plus. Most sellers specify local pickup for large heavy speakers. If you live in a heavily populated area you have a good chance of getting a local buyer. Many buyers for this caliber of speaker from a private party will want to personally inspect and hear the speakers before they plunk down several thousand dollars for them. They will need a pickup or small U-Haul trailer to get them home. You might want to list and sell the speakers first because you will have the rest of the system to demo them. Once the speakers are gone you can sell the rest of the components.
6. I don't want to insult your intelligence with common sense but be careful to screen the potential speaker buyers. Make sure that if they are coming over to audition the speakers they have the means to take them home that day. If they say, "I just want to come over and listen to them, I'll decide whether or not to buy them later" politely turn them down. Also think about whether you are OK with helping them get them out of your house and load them. The buyer may need to bring a buddy to help with the loading process. The Revels are very well known and heavily reviewed. Any potential buyer should have already made up his/her mind about buying them - they just want to make sure they are in good shape and that they work. And, I know this is obvious, but have one or more phone conversations with the buyer to establish their credibility (a good buyer will want this as much or more than you do) so you feel comfortable with having them in your house. Be sure to ask them about the rest of their system. If they don't wax poetic about the components that will drive the Revels that is a red flag. Only serious audio enthusiasts will be interested in these speakers.
7. The other components are easier because you can ship them FedEx. Make sure you note that they came out of working system and have been run recently. Everything you listed is from a well known first rate company and easily recognizable.
I'm sorry for your loss but you will doing your dad's memory a good service buy finding appreciative homes for his system. The amount of money you get will be directly proportional to the time and care you take in listing the pieces. If you can tell a story about each piece (when/where bought, any other relevant information) that will tickle the buyer's limbic system and make each piece of gear more desirable. One-owner top-notch gear in pristine condition with original boxes and remotes is the holy grail in used equipment.
