Hi alaska_guy,
Outside of PPP … one of the most important steps in buying a good quality/value mattress is to make sure that you know the quality and durability of all the materials and components inside it and if for any reason a retailer or manufacturer isn’t able to provide the information you need to make an informed choice I would pass the mattress by … no matter how it feels.
While I don’t know for certain … I believe that Sound Sleep will probably provide the information you need to their retailers (although many manufacturers don’t provide it directly to consumers) so my guess is that you are probably dealing with a retailer that isn’t particularly knowledgeable about the importance of knowing foam quality/density or that they just don’t want to take the time to find out the information.
This is one of the key criteria that would be a deal breaker in deciding whether I purchased a particular mattress or not since there is little value in purchasing a mattress that softens or breaks down prematurely no matter how it feels in a showroom or when it’s new.
I can’t feel what you feel or see you sleeping on the mattress so there isn’t any way for me to know for certain but there is more about the different types of “symptoms” that people may experience on a mattress and some of the most likely reasons for them in post #2 here that can help you with the detective work that may be involved in identifying the most likely reasons for your “symptoms”.
Based on the information in your previous posts if I had to I would guess that your comfort layers (including your topper) are too thick or soft and that the heavier parts of your body are sinking in too much and you are sleeping out of alignment. It’s also very possible that your mattress needs to break in a little longer or that you need a little more time to adjust to a new sleeping system that is different from what your body is used to (see post #2 here).
I would probably remove the topper at least for the time being and see how your mattress without the topper affects your lower back (although if your mattress without the topper is a little firmer then you may also need a pillow that is a little thicker as well to compensate and help with the shoulder issues).
Phoenix