Upmixing 2 channel

I was listening to a tidal motown playlist last night and i turned on dolby surround mode and it sounded really good. This was with only my front L&R on plus sub. I was kinda surprised by the sound.  I actually got up and walked up to my other speakers to verify that they were off.  Ive tried listening to music with all the channels on (5.1.2) and i always find my self going right back to 2.1 with no processing or anthem music mode and usually with the ARC turned off. I do find that when watching youtube or tidal videos sometimes all channel mode with some some type of processing sounds good especially with rap or classical. I guess i never tried  sorround mode while i was in 2 channel mode. If you havent guessed, i have a dual purpose system. The Anthem mrx 740 i use does have a good Sabre DAC. So I use the preouts on the avr to a 3 channel amp for my fronts. Using. A bluesound node for streaming. I know this is not an ideal set up for 2 channel. Im in the process of looking for a preamp or streamer/preamp with HT bypass to completely separate my channel listening  from the avr.  Im new to this with a preatty new system that im trying to dial in.  I was just wondering if any one else finds that upmixing 2 channel sounds good?  Could have been the playlist. I plan on trying different types of music tonight.