How about using your LFT 6 and using a high quality 4-sub distributed bass array (DBA) system like the Audio Kinesis Swarm reviewed below?
https://www.theabsolutesound.com/articles/audiokinesis-swarm-subwoofer-system/ If you have the space to position these 4 relatively small, 12"Wx14.5"Dx28"H, subs with 10" aluminum long-throw woofers asymmetrically around and facing your room perimeter walls, I'm fairly certain this high qualitybass system would be an excellent solution paired with your high quality Eminent Technology LFT 6 main speakers.
I've used this bass system for about 5 years now, initially with a pair of Magnepan 2.7QR main speakers and currently with a pair of 3.7i for both music and with Oppo 105 and 205 Bluray universal disc players on 5.1 surround systems for HT.
The 4-sub DBA concept was first discovered through scientific research and experimentation somewhat simultaneously by acoustic experts such as Dr. Earl Geddes and Dr. Floyd Toole and then further developed by audio industry members such as Todd Welti of Harmon International and Duke Lejeune of Audio Kinesis.
This bass system concept implementation results in bass performance that is near state of the art in virtually any room and with any pair of main speakers, even those generally considered too fast and detailed to integrate well with conventional dynamic cone subs such as planar-magnetic and electrostatic panel type main speakers. With 4 subs operating in concert, the bass extends down to 20 Hz +/- 3 dB, is as powerful and dynamic as the source content dictates, is very smooth, fast, detailed, with a sense of ease quality that is very natural on all genres of music and integrates seamlessly with any pair of main speakers.
You might reasonably think I'm exaggerating but I really don't think that's possible given the extremely high quality bass this 4-sub DBA system reproduces in my room and I believe will also reproduce in your system and room. It's fairly expensive at about $3K, which I rationalized as about the same price as 2 high quality subs, but it's also a complete kit that contains everything you need except the speaker cables (4 subs, 1,000 watt class AB amp with volume, cutoff frequency, limited equalizer and continuously variable phase controls. Each sub comes with conical spike footers and a port plug for operating in your choice of ported or sealed mode. I believe AK still offers a 28 day free in-home trial period that takes almost all the risk out of an audition, too.
I found the attached Absolute Sound review of the AK Swarm above to be very accurate and will give you a good description of what to expect in your system and room. I consider this the last sub system I'll ever need because I'm certain it will perform very well even if I move or change main speakers.
You can check out my system pics on my profile if you're curious about how they look and are positioned. The current pics are my former system with the 2.7QRs. I'll be posting updated pics in the next few days with the 3.7is, $3K in new GIK room treatments, a new OLED 4K hdtv and a few other new components.
Best wishes,
Tim
