I had an S901 about 2 years ago, and I sold it because it would always gurgle around low register F and below. It was a really good sounding horn, and except for that problem, I would have kept it.
Around the same time period, I tried out a S992; it was slightly warmer sounding that the S901, but I was mostly impressed with the feel and ergonomics of that horn. It had the best ergonomics of any horn I have ever played. However, the sound difference, as compared to the 901, wasn't enough for me to keep it.
I also tried a Yamaha 475 side by side with the S901; it was smaller and brighter sounding, and I wasn't impressed with it.
I just got a PM 64 about 2 months ago; it is the darkest soprano I have ever played, and has a big sound. I am having to use a slightly bright mouthpiece to make it play like I want. I read the PM 76 is slightly brighter than the 64.
So Alex, I will rank the horns I have tried/own in the order of brightest to darkest, since you asked.
Yamaha 475, Antigua 590LQ, S901, S992, Conn New Wonder II, PM SS-64. Based on my subjective ranking, I'll recommending you try out a Yamaha 475 or Antigua 590LQ, or to save money, go for a brighter sounding mouthpiece on your S901.
OO