Isolation transformers output voltage higher than wall

It's a small compact plug-in meter with a display. My wall voltage does not drift much. It typically is 121-122 volts.

I've seen those cheep plugins that were accurate and those that were not.  

Anyway, you've got nothing to worry about.  Other than your transformer may be doing more harm that good.  

Jerry

@carlsbad I always listen to music with which I am very familiar and if I sense the sound quality is compromised in any way then I won't use them.