This kind of seems like a solution (spending money) in search of a problem (will it sound good enough?)
I can't speak for those sound effects companies you mentioned, perhaps they have some technical guidelines for submissions.
Once you've conquered the basic problems like preamp hiss and that sort of thing, how does it sound to you? Prosumer gear in the right hands will sound better than top of the line gear used in a sub-optimal manner.
Generally speaking, the price/performance curve is almost logarithmic. Hardware has gotten really good (and affordable) in the last ten years or so. Ask yourself if there is a particular problem that you are trying to solve, and then approach it from that angle. The differences between preamps and converters are possible to hear, but they are far more subtle than you would think if you're just browsing forums where people are often times blowing things way out of proportion. You're going to go into the next order of magnitude on price for a 2% improvement.
Consider renting gear that you're looking at, or see if you can hear a true A/B comparison. Most moderately priced gear available these days sounds pretty excellent.