Someone on this forum please correct me if I'm wrong, but there's no channel for LFE in a soundtrack. When we say 7.1 that is what the receiver can do, not what the soundtrack that comes from Netflix or elsewhere contains. Think of it as stereo music which is 2 channel, not 2.1 although your AVR can take 2 channels music and play them as 2.1 as I'll explain later.
The Dolby Digital (DTS is the same) soundtrack consists of 2, 5 or 7 channel, or Atmos (7 + Height channels). All of these are in the
same soundtrack. If you have 2 speakers, it uses the 2 channel. If you have 5 like my systems do, it uses the 5 channel etc, etc.
You're not going to be able to fold 7 channels into 2 channels afaik and I'm not sure you'd want that. You want to listen to the 2 channel soundtrack as that is the best sound for the 2 speakers you have.
If your Left and Right speakers are good, you'll be shocked how it will sound. Gene Dellasala from Audioholics played 2 channel (was it Hamilton) or some other movie like that on his new Perlistens and he and the other person thought it was almost surround sound so 2 channel is plenty to start, trust me.
The LFE (low frequency effects) is decided by the existence of a subwoofer and the crossover point. If you don't have a subwoofer, your speakers handle all the low frequencies and try to play what's call full range. If they are bookshelf speakers, you'll hear some bass but very little although some bookshelves can dig low but are few and far between and cost a lot. If your speakers are 3 way towers with bass woofers, their ability to dig deep can vary. If you can add a sub, you can decide the crossover point(s) - essentially what frequency your receiver will switch the frequencies from your speakers to the sub. Then the sub will play the low frequencies you chose to send over for all the speakers
If you have access to streaming, play something with bass like Das Boot DJ Mellow Mix (start in the 6th Minute) and check how it slams that constant bass note on your 2 speakers. If you're satisfied and live in an apartment or the room is small, it'll probably be more than enough and you won't have to meet the local authorities. Of course, you're not going to shake your house without a sub but the bass could be great for some speakers in some rooms.
To add a sub check if your amp has a sub out port or RCA so you can add a sub down the road.
Now let's get back to connections from the TV.
eArc requires HDMI and supports the full format but you need an AVR that supports eARC (all new ones do but some older models may only support Arc or nothing). eArc is the best way to carry a multi-channel uncompressed (the best quality) audio signal. It doesn't sound like your receiver has an eArc port.
Optical/Toslink (Toshiba Link) refer to the same cable connection and can only carry a compressed 5 and 7 channel signal but only 2 uncompressed channels. Since you only have 2 speakers, Optical supports 2 uncompressed channels and that's great for you as it's a perfect match with your speaker count.
Does your receiver support Optical? If so, you're good to go.
If not, then you need something that will take the optical sound and convert it to a regular RCA (left and right) connection that you can use to connect to the receiver.
If you don't have an Optical or HDMI, then maybe there's a device that can help you but Denon has an AVR for $300 that will handle 2 channels over eArc and might be your best bet. You could go for used gear with optical to get better sound but they are such a gamble that I'd stay away from it unless you live in a city and you can test the equipment before buying it.
