So basically making a stealthy character is just a concept that can not work here?
It can work, just not against anyone who does not want to be spied upon.
Anyway, by my own count. If you have the best available gear for move silently then your total from items is +30.
That's insanity and should be enough, I have never taken issue with the gear available and would not resolve any imbalance there.
+30 MS from items (belt,armor,boots,bow,ringx2,cloak)
30 (items) + 5 (feats) + 2 (background) + dexterity modifier + 3 + class level = sneaks unbuffed move silently.
I think a good reasonable estimate is ... a character at level 12 with a 18 dexterity and the amazing fortune to get all the best stuff.
56 is the value. If using buffs you can reach ~62.
Its not hopeless, that will work for killing others, however it will not work nearly as often for spying. In my experience every group worth dropping an eaves on will have their own sleuth dropping down claireaudiant amplifications before anyone says anything of value. Stealth is much more valuable for assassinations than for spying.
Listen items of best combination gives +20, more likely +18 for most listen geared folks ten less than MS in total but amplify and clairaudiance alone is more than enough to make up for the deficit and the feat deficit and a good portion of the skill point deficit. I don't even whine, I don't play a sneak very often at all anymore, but I have known for years the balance was broken when the listen rings were made. MS can not compete with Listen now that the gear is closer to each other. A ~20 advantage to MS over listen in gear is the only way I know of to make it a competitive roll that rewards build over item accumulation and the rings are in the game and not going anywhere so its what it is.
For spy scenes you are better off emoting your rolls and the others counter rolling since you have a reasonable chance of success 1 roll v. 1 roll instead of the constant checks the engine does. But eh.... people who know you are there modify their behavior even if unintentionally, its subliminal and natural.