Thinking of adding a sub---maybe not?

Properly set up good subs actually improve the performance of the main speakers but only if there is a high pass which takes a huge load off the woofer of the main speaker(which is why its performance is significantly improved) Some sub such as the RELs do not use a high pass filter so I'm not a fan.

And I'm not a fan of reflex or passive radiator subs. They sound like more bass but it's boomier than a good closed box.

There’s a difference between bass punch and sub bass.
Your Lore reference should be able to provide bass, but room acoustics and placement can effect the amount of bass they provide.
The sub creates the lowest frequencies, greatly contributing to realism and environment, but full range speakers are delivering the bass guitars, drums for the most part.
My parasound allows me to adjust sub gain and to toggle the sub off or on from my listening position. This has allowed me to truly discover and appreciate how much bass punch my standmount speakers (Kef q350’s) are actually delivering.
My Rel sub is great, and it’s on all of the time...but not necessarily for bass punch.
If your speakers or placement are deficient in that area and you can’t get it worked out, consider different speakers or one of Schitt’s tone controls. The 4 band loki mini or the new 6 band LOKIUS may be what you’re looking for.

I just looked at your model of Luxman online and see that it has treble & bass controls. Does the 8 dB of increase at 100 Hz still not help, or is it degrading your sound?

I have just added a pair of REL Carbon Limited to my system. Even though my Focal Sopra 3s go down to 30Hz the subs have helped my system drastically. I use an Anthem STR integrated amplifier with their ARC room correction so the integration with the mains is excellent. The ambiance and flatness of bass is greatly improved. The ARC has crossed over the Subs at 70Hz with the mains. And room correction is only enabled up to 200hz. Maybe I will also play around with the crossover and see if I can bring it down to 40-50hz and leave the subs playing below that. But right now the improvement with the Subs is very good.
If anyone has any suggestions on the crossover point for my setup please do share.

I use 2 RELs and agree with REL's philosophy of letting the main speakers work to their natural limits and simply dial in the subs where the main speakers drop off due to their design. And use 'em in mono to keep standing waves at bay...works for me for years and they simply disappear when adjusted properly. 

@mwinkc Thanks for the input--I've tried adjusting the tone controls but just I wasn't too happy with it. Hence, thinking of the sub. I realize my room acoustics is playing a part with this too. So a tweak here and a tweak there has affected the sound---some good and some not so good. I'd like to at least try a sub from a dealer with a return policy just in case. Great suggestions on here btw---thanks again!