Background noise.

One of the amps in What used to be my primary system developed a transformer hum and it drove me crazy. The amps are from the eighties and I had them serviced a few years back and I asked the tech about the hum and he said what hum?  To me it’s very noticeable anywhere in the room and he had to have an ear right above the transformer to hear.  Someday I have to replace that transformer (about $550) but I’m in no hurry.

Great topic and probably the most cost effective means to improve listening sessions.

I never listen to music when others are at home. In fact I never go into the 2 channel room when my wife is around to remind me how I waste money and how ugly the bass traps are. Music above quiet levels gets up the ire of my daughters. So, not much time to listen, but when I’m alone, air filters and humidifiers get switched off and it's quiet

As someone who did acoustical consulting, this is a favorite topic. In particular, doing battle with architects an interior designers who rely on HVAC noise and in some cases ambient noise generation to create some sense of privacy in open office environments. How anyone could believe that adding noise makes for lower stress work environments is completely beyond me. In one case the ambient level from HVAC was over 65 dBA throughout the facility, and it was billed as a 'quiet' work environment. It took over a year, dozens of employee complaints, stress related  sick days,  and even employees quitting before management relented and implemented my design. We reduced the ambient to below 50 dBA, and within a couple months productivity, employee satisfaction, and even attendance had improved measurably. 

Also, regarding high efficiency systems, they benefit greatly from being properly gain staged so that you don't hear noise when the system is idling. Ideally, you want your preamp/line stage to clip within 3-6 db after the power amps. It's common to see preamps operating 10-12dB or even more gain than is necessary, and that robs the system of that much dynamic range and results like hissing horns at idle.  Turn the amps input sensitivity down, and drive the preamp harder. That leaves the noise levels down.

@panzrwagn

Wow, what a story. Add sound to create a sense of privacy. It is incredible what some people will come up with. I now wear my noise cancelling EarPods when I walk the dogs and go on bike rides. The lower noise level relaxes me… while the background is more or less white noise… it kind of “jacks me up”… not relaxing.

One of the most profound improvements in my professional life was getting Bose Quiet Comfort headphones (I flew over 250,000 miles a year). I would put them on when I got to the airport and take them off when I got to the hotel at my destination. Huge improvement in my life! Lowered stress. Most of the time I had nothing playing… just noise cancellation.

i bet the majority of y'all have perfect hearing and not a trace of tinnitus. not me. that said, i am a big believer in living out in the woods to get away from city/suburban noise. those are the big noisy dogs that, once those are out of the way, then the domestic sounds [HVAC, refrigerator, line hum] take on a much bigger presence. i have found that the best and most practical way to deal with those, is to use an audio [dynamic range] compressor on the audio, to bring up the music buried under the ambient murk. otherwise, one has no other choice but to turn up the volume and possibly [further] damage one's hearing as well as disturb the neighbors. a 90+db dynamic range is totally impractical for anybody living in any real place where the 90% can afford to live. a modest amount of dynamic range compression is useful in majority of listening environments.