Receiver Too Weak?

Sadly, I think you need more receiver, it's under 100w @ 2 ch, usually if you drive more channels the power will be even less. Your speakers have low sensitivity, so they need more power to sing. 

You didn't really say if it's music or movies that are the issue. If you are only running 3 speakers, or something else. 

Setting up a HT system is a ton of work, you have several speakers to place, a ton of wires to run, some of them are LONG runs. Setting all the individual speaker levels, each speaker crossover, subs, etc.....

It's a serious process that takes a lot of time, effort and skill. A good starting point is to measure out the listing room, place the speakers, measure them to the listing area, try to get them all square. Then run your room correction. Listen to it for a bit, adjust as needed. For the center speaker, try to keep in inline with the front L/R, make sure it is open to the room, no reflections on top or below. As in a shelf, or cabinet. If it is, pull it out, so the drivers are in front or at least flush with it. Is there a coffee table also in between you and the center? Move it, and see how it sounds, or put a blanket over it. Seriously it will sound very different. Then adjust all the levels to suit you. 

Than rinse and repeat. Different sources, different services sound so different. My HT receiver has a couple pre-set stores for settings, I adjust them a bit for the source. Like Netflix's usually needs more bass, and center ch. Amazon needs less bass, and center, also dynamic compensation. That is unless I want the room to shake. 

We didn't even get into cables, subs, room treatments, etc...

FWIW, I have a 9.4.2 setup, sadly I fiddle with it almost every time a movie starts. 

The dialog in video can challenge even a very high end HT or 2 channel system.  I improved it by upping the output put from the center channel in the settings of the AVR.  Since center channels are mainly for speech and not much involved with music, it doesn’t alter the musical content.

Op,

Here's my short list to solve what I'll call your HT amplification problem: Can't hear details (dialogue, or otherwise), (plus, maybe weak soundstage?): 

1. Mostly HT: high sensitivity speakers for sure (95db or more)

2. Size of your room?  Sm/Med (Your speakers w/ subs (+ AVR/amp of 200w or more); Large Rm: floor standing 3-way speakers (DefTechs are great for movies, not so great for music) + Sub/s   with almost any AVR not less than  100w/ch for ALL surrounds (which really means you'll need an AVR or amp pushing 200w/per anyway).

3. Subs ALWAYS for HT.  I recommend 2, but you have a large SVS, so may be fine.

OP-One more thing..(my Columbo...)

I really got as big boost in my HT system when I used the pre-out to a separate 3 way amp (It was an Acurus 200x3) to handle the fronts and center channel.  I mean EVERYTHING changed then and there.  My setup was a Denon x4500h (still in the system handling TV sources) and the Deftechs: 9080x fronts, CS 9040 and SR 9040s for a 7.2 system.  The fronts had 12" woofers but I still used  2  8" subs. 

Just consider what you've been seeing posted so far:  If you want a great HT system you need high sensitivity speakers and a moderate to high-powered amplification from a outboard amp or heavy duty AVR.

Again, good luck!

First, thank you all for the responses and sorry for being slow to respond myself. I think these are the answers to the questions I saw…

1. I don't really listen to a ton of music on the system. I watch tv/movies and play video games. 

2. The sub is a Martin Logan (https://www.martinlogan.com/en/product/dynamo-500)

The floor speakers are bi-amped and the setup for it in the receiver settings is done. Should I undo that? If I understand correctly that would reduce the power which will make them perform worse, but maybe the balance will be better until I can improve my equipment? Or does bi-amping not really work as well as it sounds like it should?