Aaron – Greetings and Happy New Year.
The biggest issue I see is the size of your room – 40’ long × 19’ wide is large. But equally important, when you listen, where do you sit? On that red sofa? How far away is that from the nearest pair of speakers? If the distance between speakers and listener (on the middle of the sofa) is more than about 12 feet, they will likely sound small and inadequate – like the music is coming from tiny musicians inside those small speaker cabinets, playing tiny instruments. When you’re sitting on the red sofa, how do those speakers sound compared to your headphones?
Your Yamaha receiver is only modestly powered, probably inadequate for such a large room. It is rated at 70 Watts per channel when 2 speakers are being driven (8 ohms, 20 Hz-20 kHz, 0.09% THD, 2-ch driven). When you play music, do you use two speakers, or all four? When driving four speakers, the available power per channel will be lower.
Live with your vaulted ceilings and wooden trusses as they are. They cannot be easily altered or treated. A vaulted ceiling may not be as much a problem as you think. If the ceiling and floor are not parallel to each other, it can allow better sounding bass that if those two reflecting surfaces are parallel. Replacing your receiver with something more powerful is the best treatment for a very large listening room.
Those Mission M71s are decent enough speakers if they’re in a much smaller room. Do they sound better if you’re in the kitchen than on the other side of the room?
As shadyj already mentioned, those speakers will sound better if they were lower, roughly at the same level as your head. The same is true for most any other speaker.
Ignore the so-called low-hanging fruit that you mentioned, such as that overpriced electrical outlet. They’re a waste of money and time. Similarly, you can ignore bi-wiring speakers to the receiver. That adds complexity to your system without providing any improvement to sound.
With a budget of $2,150, I think you should focus on a new pair of speakers for the sofa side of your room. Keep the same speakers in your kitchen. After that, look for a more powerful receiver or amp.
Your wife’s insistence of wall mounting speakers high above listener’s heads is a major problem. If they are lower and closer to listeners seated on the sofa, there should be a significant improvement. If your wife does not share your interest in audio, then ‘her way and only her way’ is not a reasonable compromise. I leave that up to you.
Have you considered moving the red sofa closer to the speakers?
Larger bookshelf style speakers mounted on stands, take up no more floor space than floor standing tower speakers with a similar foot print. I think that would be a reasonable compromise. There are speakers, as well as wooden stands, available with finishes that would go with your midcentury wood home furnishings.
To replace one pair of Mission speakers, I suggest
Philharmonic Audio BMR monitors. They cost $1,750 per pair, are 20" High × 8" Wide × 12½" Deep, and weigh 32 lbs. each. To wall mount them, you would need small shelves sturdily attached to the walls. Floor stands would work better.
The guy who designed these speakers (and others) also lives in Glen Echo, not far from you. Contact Dennis Murphy (see his email address on that web page I linked) to arrange a visit to hear them at his house. He can fill you in on what finishes are now available.
