The shelters here give you a certificate for a free vet check when you adopt a cat from them, did you get one? If your cat is eating and drinking well, acting curious about her new surroundings, she's probably fine and the muted meow is simply her way. However, if you have a free vet visit, it will make you feel better for a vet to say there is no problem. How long ago did you adopt her? She may be keeping a low voice while she gets used to her home.

Is she full Siamese or a cross with another breed? You do expect that breed to be very vocal - perhaps you should be glad that she does have a small meow since a Siamese talker can drive people out of a room! My Siamese, adopted from a shelter when she was already in her teens, just went through radioactive iodine treatment for an over-active thyroid and I'm sure that her meow is now much deeper, which worries me a lot even though she's fine in every other way. However, I just can't remember her old meow with any certainty, so I'm trying not to worry about it. Anything other than the usual meow does bother cat owners particularly since cats are notorious for not showing they are sick until they are ready to fall over.

Anyway, congratulations on adopting Moxie and I hope you both have many fun years together.