Budget is important else you're asking people to waste their time suggesting ideas above/below what you want.
For best listening a stereo pair if best. It's a different prospect if you want to fill a large room with speakers at both ends. It can be accomplished. Monitors may very well be the best option for filling a space like you have like a PA system.
Bit of Forum etiquette, no need to use a bold font.data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7
"Dedicated listening at modest levels and mostly me".
This suggested that you would have a seating position in front of the speakers and that is where you would do the listening from. Therefore, for sound quality stereo (2 speakers) is always best adding another stereo pair just muddles the sound particularly if you have 55' between them, that is a delay of 1/20s which would be noticeable (slight echo).
If you just want to fill the room with sound rather than trying to get the best sound in one part of the room then as others have suggested a PA system may be the best way to go.
Its also worth pointing out that acoustically the big space does help if you go for a dedicated listening zone but hard floors and windows will detract form the sound. Judicious placing of rugs and furniture can help.
Thanx everyone! I couldn't figure out this stuff myself if my life depended on it.
Your concept - self-powered speakers using Chromcast - works regardless of price-point. I think I'm committed to buying 1990's speakers, for as little $ as possible. Which from 1990 will be challenging. But I know where to look. My default is buying high-end, newer speakers used or new. I can afford about anything but I have an ideal to beat the system! That's the way I am. I'll go with 2 speakers. I'll figure exactly where to put them, today. I need very high fidelity so although interesting I won't be getting monitors.
Question: are you sure I won't need a pre-amp, being that the cell phone is a weak source?
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I thought monitors is synonymous with PA system, which is not high fidelity.
That's really not the case. Some of the most accurate, highly regarded speakers are active studio monitors. Check out reviews for the likes of Kii three, Event Opal, ATC SCM40A, thebig Genelec, Adam and Focal designs etc.
Also, a few PA systems are considered to be sonically accurate too, such as the Funktion one system.
So, using monitors, and I have recently recorded in studio's, where do I place them in my situation? In a large room would it not have the same delay mentioned above? Thanx.
Oops it looks like Chromcast needs an auxiliary port on the speaker. The vintage speakers I've seen don't have one. And only some vintage speakers are active. I think my options are narrowing, without buying on eBay vintage, mail order - the largest collection of vintage I've found.
If you are set on "vintage" speakers, you are correct that the vast majority will be passive i.e. they need an amplifier to make them work. So, simplistically -
Data is stored in either an analogue or digital format and need a device to extract that.For analogue this is likely to be a turntable, tape deck, FM /AMtunerFor digital this can be cd player, sacdplayer, DAB tuner, streaming deviceThese are all classed as sources and provide a small voltage output (less than 2V typically) that need to be amplified to a level that can drive the speakersThe amplifier cam be in one of two places - stand alone connected typically by long wires to the speakers (classed as a passive setup) or built into the speakers connected by long wires directly to the sources (classed as an active setup). Sorry if I am teaching you to suck eggs but sometime getting a grasp of the basics will help you decide what you want.
So, set yourself a budget, decide on the type of system you want (passive/active/sources/features etc. and what you want from that system sound wise/musical tastes/useage/room etc. and then you can go window shopping in the various online and bricks and mortar establishments to creat a short list for audition/serious shopping. (Once you have this you can also post on her and ask advice, but do bear in mind that this forum is predominantly UK based and so response may need a little more effort by yourself to find out if they are viable in the US).
Hope this helps.