Several years ago I recommended to a friend that they purchase an Onkyo tx-nr636 receiver for their Home theater setup. I configured the system for them and it worked well for several years. They then remodeled and went with a sound bar and took the tx-nr636 out of service. They gave it to me to check out before giving it to a friend who was looking for a stereo system. I hooked the tx-nr636 to some decent speakers and sub-woofer in 2-channel Stereo mode to check it out. It played ok but lacked the power that a 90+ watt receiver should have and did not drive the sub at all. I configured the tx-nr636 wireless feature to connect to our home network and then initiated a firmware upgrage for the unit. The upgrade affected multiple components on the tx-nr636 and took a total of about 45 minutes to download and install. I was not expecting much of a change after the upgrade but was (very) pleasantly surprised. The tx-nr636 played with much more authority after the upgrade and the sub woofer is now functioning normally. The change was NOT subtle, more like a night and day improvement for the unit. When I initially installed it years ago I upgraded the firmware then but it was a brand new model at the time and apparantly a lot of improvements were made to the firmware in the meantime. If anyone out there owns a tx-nr636 I strongly recommend you upgrade the firmware!!