I've designed several phono preamps (including the one I now use), and I can say pretty confidently that the differences, while subtle, are real in terms of sound quality. However this has more to do with the topology chosen for a design rather than other considerations, such as the amount of money thrown at a design.
ICs sound different than discrete transistors or tubes, but all IC designs (within limits of good design practices of course) are going to sound virtually identical because of the large amount of negative feedback involved with this type of design.
Discrete transistors (and FETs), and especially tube designs, are going to have more obvious differences in sound quality between these different designs.
However - and this is the important part - none of these design topologies are going to cost a lot of money, relatively speaking, to build. It's very, very hard to "throw more money" at such a simple circuit and realize any "better" sound quality. Contrary to what many manufacturer's marketing departments would have us believe, "designer" resistors, capacitors and associated parts are _not_ going to effect sound quality one way or the other. However, using these "designer" components is going to add to the cost of the design.
A competent design in the first place, regardless of the "cost" of the parts, is going to swamp any differences made in sound by making a design of more complexity, or cost, than necessary, In fact, there is a lot of empirical and objective evidence that points to the fact that the simplest designs are the ones which are likely to sound the best. The sound quality of such simple circuits as single ended triode power amplifiers bears this out.
The limit of any "improvement" in sound quality is reached by using high quality, yet not overpriced capacitors (polystryene, polypropalene), and 1% metal film resistors. However, using such competent, verses overpriced, components gives marketing departments nothing to crow over.
I might add (from personal experience
) that the Outlaw products represent the best of this competently designed approach.