Forgive me putting my "non Player" foot into this but when I worked for a Unversity that had Instrument making courses (including Guitars, both Acoustic, classical and electric) it was a settled policy of the Music Technology department to invite , and pay for, Professional Guitarists and other instrumentalists to come in at the end of the examinations in the Final year and Play the instruments of the Graduating students,in that way the students got a chance to hear how their instruments Really sounded and also to get a good comparison between instruments. Sometimes the differences were VERY large, and somtimes negligible, but it was amazing what a professional could coax out of an "indifferent"(on the test bench) sounding instrument .
One year the had a distinguished professional Harpsichordist to play 3 New , student built, instruments,mostly Bach and Scarlatti and when the recital ended and there were just a few Technicians left clearing up he started playing Jerry Lee Lewis's " Great balls of Fire" on a 2 bank harpsichord!!! and It sounded like it had been written for it!!!