Not in love with my system yet. Help!

Hello,
first make sure the second sub works ok but using it where your first sub was. Next you should hook up your surround receiver to the subs using the RCA out/s or add a splitter if needed. Next, your T7i came with speaking cables that hook directly to the amp speaker binding posts. Call parasound and ask which ends from the speaking to use. ( when you have a linear balanced amp you don’t hook up the black or negative wire) last but bot least look up sub crawl. The T7is are active forward firing with passive down firing. The bass waves travel far. Like 50 ft. You need to Google sub crawl to figure out the best positions for each of the subs. A teaspoon of sugar is good a pound is too sweet. Same with subs. If you can hear where they are turn down the level or the crossover or both. Topically they tell you the knobs start at the 10 o’clock possible. Two are better than one once you adjust/ position them correctly. 

I’ve got a Ti9 hooked up using REL’s proprietary cable which taps off the speaker terminals on the amp.  Designed to integrate into a  2 channel system more evenly / musically.  The subs can also be hooked up at the same time for HT via LFE / to the AVR receiver.  
OP - best advice I have seen is cal REL, they are very helpful.  If 2 channel listening is your main goal, at first anyway, use REL’s proprietary system to hook the subs up, you’ll do that off the Parasound Integrated.  Get them both working, experiment with placement and settings.  The TI series will work with HT but it’s claim to fame is 2 channel and their unique hook up / integration with the amp / speakers.  You’ll find many posts / reviews where adding a second REL sub to 2 channel listening has taken a great set up to the next level, I’m sure REL can help get you there.  Make sure to take advantage of their recommendations, again, these subs are designed specifically for 2 channel and their reputation is built on seemless integration, following their set up guidelines is key.  I find mine is fantastic for music / 2 channel and forgettable in my HT, if I can’t have my cake and eat it to I want it rocking in my 2 channel. 

@havocman Thank you for your constructive criticism. I will take your observation under serious consideration. Cue eye roll.

@thecarpathian Yes!

@reubent Correct in every aspect except for one. I initially hooked up the REL as directed with the Speakon- Neutrik cable and got it dialed in pretty easily. I did not run Audysey in order to achieve this as one has nothing to do with the other according to REL. They are designed for this type of application. After I got it set up for 2 channel I didn't run Audysey right away because I knew I was receiving the 2nd sub the next day. Hooked it up as directed. I've tried a few different spots for it and even moved the 1st one to get me where I need to go. I wasn't really satisfied with the sound but went ahead and hooked up the RCA's to the Low Level inputs from the sub outs on the integrated. Audysey wouldn't recognize the 2nd sub so I went directly to the Denon sub outs which corrected that issue. After running it the sound for HT was pretty spectacular but of course that doesn't do anything for 2 channel as the Denon is cut out of the equation. If I'm understanding what Audysey does it corrects for room (nodes?) and delivers the low frequencies in the proper manner to my listening position. If this is correct it tells me positioning of the subs is the biggest issue. Now, if I can manage to get these subs dialed in properly for 2 channel I should be able to run Audysey again and have it correct for when in HT.

@p05129 The only way they would be running at the same time is if I had a source running from the Denon at the same time I was listening to music. They don't recommend you do that of course.

@crn3371 These RELs are designed to do just that. When they are integrated properly they will provide all of the explosions and bullets whizzing by your head when in HT but disappear (blend) with your mains when in 2 channel. 

@cwory I have been in touch with them and they are helpful but all they can do is verify I have everything connected properly and suggest I experiment with positioning, crossovers and gain.

As far as millercarbon goes I can take the good and the bad isn't too bad. If you haven't read through the comments of his virtual system you might be more dismissive of him than you should be. I will continue to try to learn from everyone including him.

@hshifi I did the sub crawl yesterday and am thinking I will employ that positioning as soon as wifey clears out all the Christmas decor. One issue I realized with at least one sub is I am at least 20' away where I found a good spot with good resonance. I will either need to get a longer RCA or leave it disconnected on one which mean only one sub will be doing double duty.

@mm1tt7 I am in the same frame of mind. It is more important to me to get 2 channel correct but both should be doable.

@erik_squires Thanks much! I wasn't aware of that and I think this is going to be a big part of the solution. I know they have several products so is this the one you would recommend?

Speaker level connection for REL subwoofers isn’t set in stone. My 2 channel system is powered by an Anthem STR integrated amp. I have my 2 T5’s hooked up to the subwoofer outputs on the amp so that I can take advantage of room correction. You also wouldn’t want to use the Speakon connection in a home theater situation as you want to be able to take advantage of the LFE channel(s).