Thanks Wayne! I think what I'm hearing has always been there, but more noticeable do to the efficiency of the speakers. Good to know it's not the speakers. I'll follow your advice & see if I can isolate the hum source. It very well may be the older amplifiers are producing some noise.
My home is fairly old and there is no ground connected. There are a lot of electronics in the room where my stereo is setup. Not sure if there is some type of interference going on. I believe everything is connected to the same wall socket but some equipment may be plugged into different power conditioners. No video sources are tied to my audio gear. I'll start by unplugging everything not in use and go from there.
The speakers sound awesome. Put several hours on them today. Seem to be getting better & better. Thanks again!