Chair or Sofa? Which do you use?

I am planning to set up a new listening room; approx. 13 x 20 w/carpeted floor. Do any of you see any advantages of one of these seating arrangements vs. the other?
If your intention is romance, even occasionally, go with the sofa. Otherwise, chairs are the way to go as long as they are comfortable. It helps if they are also easy to move so you can share the sweet spot with a friend. While listening alone, you can claim the prime spot yourself. With chairs, you will be able to sit more comfortably very close to a friend so you can both better enjoy the music.
Sonically, I don't think it makes much difference. Sitting exactly in the sweet spot typically does. This is especially true (and rewarding) with narrowly focused speakers such as the Dunlavys.
You have got to do the sofa. Whether it is romance or sleep or kids over to your house, the sofa is infinitely better than the chair. Think long term. good luck, mike.
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Sofas don't allow you to recline. You are always forced to be upright even with your feet up. Sometimes I like to lay back in a darkend room and relax to music. You have to lay side-ways with a sofa and one ear is always down. I chose recliners from Natuzzi that a local Scandanvian furniture store sells. They have adjustable head rest and fully recline. Becareful that what ever you chose the back is not too high. If the back is higher than your ears, it's like putting your head against a wall and listening. All of the first order refelections will hit your ears. I chose chairs with backs lower than ear level. If you sit in any sofa and the back is even with or higher than your ears, it is compromising the sound quality. So make sure that you get a sofa with a low back if you go that route. I have both 3 chairs in front and the sofa on a platform for the guest who don't care about sound quality .
Reclining overstuffed throne for solitary listening which switches places with the adjacent love seat when my wife or son wants to share the sweet spot.
Overstuffed cushy sofa. It acts as a wonderful acoustic damper for the rear wall. I also have my speakers set-up for "nearfield listening", so this really helps!
The Back Chair (leather), in the "sweet" spot. I believe when you use a sofa for "romantic" listening, it's called the "sweat" spot.
Sonically it does make a difference, as does all the other furniture in the room. I would suggest a sofa, if the room is not otherwise stuffed with soft, cushy furniture and drapes and things. The room's acoustics is a factor way more important than all the wacko cables and crazy isolation devices you can shake a stick at. So take care.
I always sit naked on a solid 5" thick maple plinth with four 2" brass cones underneath me (IMPORTANT: The points face DOWN!!), and cover my body with Marigo Tuning Dots (I found the 32mm ones work best). The soundstage is unreal.... pinpoint imaging and tight bass to write home about!

If romance is your intention Ozfly's recomendation of the couch is definitely a better way to go, but you can still have alot of fun with those tuning dots!

I tried Jax2's seating recommendation. Found out that if you also Shave your entire body hair, & cover yourself with thin coat Johnson's Baby Oil, the Music seems to just Flow better! Make sure to use atleast 4 Blu-Dots on your Bum for secure positioning! ALSO IMPORTANT - make sure your spouse is out of town! Otherwise you look like an UFO ABDUCTION VICTIM if discovered! Will try an auto wax next called Liquid Glass see if it works better than baby oil?
Audiobugged, would the correct choice for wax or oil depend on the current absorption characteristics of the room and one's percentage of body fat? Being a little north of the ideal body fat ratio, I prefer wax since it is more reflective than oil. There's no sense in adding an unneeded bass trap in my environment. By the way, I also recommend heavy drapes for both acoustical purposes and to avoid those unpleasant incidents with the neighbors.
As of last year I'm now with Bulldogger on the recliner question, though I like to have the headrest available - I don't know how you could recline without it unless you wear a neck-brace while listening. The sofa does give you the multiple listener option, but I don't require that, and I like to have someplace comfy to rest my arms. Though I don't doubt that having something right behind your head does change the sound a bit, if that something is sonically absorptive, it should be fairly benign. Besides, when you fully sit up the headrest is not against your head, and when you recline it is no longer close to being at a perpendicular angle toward the direct sound arriving at your ears. Anyway, I find the ability to recline and put up your feet to be very conducive to letting yourself dissolve into the music without getting fidgety, looking at your gear, playing with the remote, getting up to change something, etc., but the flexibility of a recliner allows to listen upright when that is best. I also like the fact that it permits you to adjust your ear height relative to the tweeter axis, though you have to compensate for the difference in distance as you recline, so the same chair location may not work equally well for both the reclined and upright positions. I thing an intermediate position is best overall - go too far back and down, and you'll want to fall asleep...
When not trying Naked Audio Tweaks, I searched for about one year till I found the most comfortable Non-Fatiguing listening chair. A leather Recliner made by a company called Calia their Monda model. It has a multitude of listening positions & looks really kewl with it's brushed aluminum accents!
An Ikea chair. You know, the bouncy ones with the wooden frame? They kinda' rock and move with you as you move with the music. I hate a chair that won't move! They are also light and easily moved out of the sweet spot when you're entertaining.
Ikea offers a variety of fabric or leather coverings, although leather might be a little sticky for you nude guys.