Question For Those That Watch Movies/TV Through Your Two Channel System

I use an poke TV as source.  A few years’ old HarmanKardon AVR. With a PS Audio S300 amp running L/R JBL 590.  The AVR runs the surrounds and sub.  I know this set up is not ideal but it does sound good. No need for a center channel. And Tidal runs in 2 ch mode.  It works great in 4.1 as well. 

Rats. I use Apple TV as the source. 

I hope the OP can read between the lines. The answers given here are correct for the most part although they might sound contradictory at times. Everyone is speaking from their own particular prospective, but not necessarily from his.  So let me try to be more flexible. If the system will be used mostly for music and for one listener, you probably would be fine without a center channel. On the other hand, if the system will be used for at least 50/50 music/movies, you should seriously consider a good center channel speaker. The idea that any integrated amp has a better preamplifier section than an AVR is not accurate. Owners of Datasats, Trinnov Altitude, Theta Casablancas, Marantz 880x, Lyngdorfs and many others may disagree. It certainly is not a given. These AVRs all have very capable preamp sections. Coupled with their DSP features, they can satisfy the most demanding audiophiles out there. 

I've run a stereo line from my DVR to a 100 watt (supposedly) receiver to an older but great sounding pair of Boston Acoustics A60s (replaced the woofer once) on stands for years. Excellent stereo sound for tubbage.

Thanks for all your suggestions. The Power Node might be an option or maybe upgrade the AVR. Another option would be to move his Yamaha Integrated from the turntable system and try it in the HT system for a while.