I have a Pfaff 7550 that is not too quiet. For Christmas, I bought my daughter a Janome Sew Precise on eBay. When it came I tested it to be sure it was ok before I gave it to her. That little machine was alot more quiet than mine. Maybe
because it was new, I am not sure but it was quiet. I was tempted to keep it but it doesn't have needle down/up. That was the only drawback.
Why not check out machines at dealers and try them out. You could at least have the joy of shopping.