petrof uses 1st rate materials, but the production quality contr

is not as good, unlike yamaha. voicing means adjusting the tones (different from pitch adjustment as in piano tuning), by working on hammers and action mechanism.

because of the lack of uniform quality control, petrof pianos have more individual characteritics, some are very good and some not. by tonal adjustment, one can get a better piano. steinway has similar issues.

need a good technician to do it, local dealers should know. good luck.