I have two Suns housed together since fluff balls. Even so, "I" am their flock, or mommy, or whatever. I am sure if I worked on it I could lower the volume a little, but am not sure how much.
We live in the country and it is just the two of us so we have chosen to not fight this battle, but we have tried to tweak the odds to our side. When they flock call us we always responded with "okay", so now instead of screaming for an hour, they will call out okay. I also say "good morning" every morning and they reproduce that with incredible clarity. That has also helped. Your little guy may be a bit young for talking, but a soothing flock call return is of great help, perhaps a whistle or "okay".
Cartoons. We have cartoons on all day for the birds to watch. This keeps them quite entertained, although we had to switch it up a bit at first to see what really attracted them. They love this one that plays all day with a green bad guy. They will all yell when his face is big on the TV but it is not at the flock call volume, more for fun.
Lots and lots of chewy toys and foraging. We recycle a lot of cardboard around here for the birds. The more they can thoroughly destroy something the happier they are. I have at least four different food sources to keep them busy, sometimes more. Each food source has a variety of tastes and textures. I try to change it up a bit. Today I made a bean/brown rice/wild rice/quinoa/dehydrated vegetable mix in the rice maker, they love this and the warm food seem to calm them.
Baths. For some reason, a good bath quiets the beasts. I think it just makes them feel good and takes their mind off of being in jail (our Suns spend more time "in jail" then our GCC just because they will attack strangers and we have a business we run out of our home. My best employee finally threatened to leave when Winston nearly tore her ear in half).
Short supervised times out of the cage when you can, and as much time out whenever feasible. Mine are also near a window where they can watch traffic, the sheep and horses and wild birds and such.
A dependable schedule, as much as you can, and doing things in a dependable manner. Cleaning the cage at the same time, feeding at the same time, time out of the cage at the same time, stuff they can depend on to reduce their anxiety of not being with you "right now". Also, having "stations" throughout the house so they can travel around wherever you are.
Eating with the family. This seems to really satisfy something very base at its core. Its what birds do.
If they are wound up at night time we pull their curtain and play lullabies and sing to them, just for a few minutes. It definitely settles them down.
My conures are a ton of work, more so than any of my other critters and I still feel like I'm not doing everything right. If I had known about the Suns in advance, I would have gone with one, if at all. But they are here are are my children just as surely as my human ones and it was my fault (and my husbands) for not really DOING the research, which is totally unlike us. Lesson learned but it will be a 30-40 year (hopefully) lesson.
There are so many positives about Suns too. So so smart. Smarter than me. Beautiful, no doubt. Total jokesters, they just make you laugh. Very loving and loyal. If any stranger were to enter this house they would let us know before one of my 4 dogs. So snuggly (in general). The variety of ridiculous noises they make is crazy (not the loud ones). There just all around good guys. My Suns have never laid a beak in meaness on me or my husband, Pickles my GCC has no hesitation in nailing you, but not to the point it hurts, she is just more dominant.
I hope something here helps. Good luck.
-Jen