If considering a used Phonostage, which is not a bad idea. It will most likely be one that is outside of a warranty period.
With the warranty period spent, it makes the idea of modifying a model more attractive.
Any used models on the shortlist can be checked out to discover which are being altered by using circuit mod's done by others.
Modifications can be done in various ways. One, might be a send away for the mod', another a DIY method where a local skilled individual is capable to produce it, or the final option a DIY undertaking.
This can be a very cost-effective way to achieving a design that might even surpass more expensive models' performances from the same Brand and in doing so, produce an end product that surpasses, as well as competes closely to a much wider range of Branded Models.