Here's a quickie improvement you can make in under 10 minutes and it is guaranteed to improve the sound of your system instantly. Really.
Shut everything down and one by one, unplug and replug everything back in. Interconnects, speaker cables, AC power cables. If it's part of your system, disconnect and reconnect and then turn everything back on. You'll be amazed at the difference.
This is a process many of us know about but just get lazy and don't do as often as we should. I do this about once a month. I actually set my phone calendar to remind me and the fact is, even once a week isn't too much. It's one of the best and easiest tweaks you can perform.
It works because over time some connectors get oxidized while others succumb to pollution in the air. Even gold to gold contacts, sound better if you practice this faithfully.
It's free, takes only a minute and you'll thank yourself every time you do it.
Just like washing your car.
