Hello majorc,
Your description of your current system's shortcomings are remarkably similar to the perceived shortcomings I had with my system as formerly constituted, although I used more powerful ss amplification with my Magnepan 2.7QR planar-dynamic speakers.
I believe your ET LFT8bs are also planar-dynamic type speakers that have the 2.7QRs similar strengths of having fast and detailed midrange and treble performance along with very good, palpable and natural stereo imaging qualities. But I also believe they share similar weaknesses of having restricted rated bass extension, mine are only rated down to 35 Hz, and having rather poor bass dynamics.
About 5 years ago, I bought and installed an excellent solution that dramatically transformed my system by providing the solid,powerful, rhythmic, fast, detailed and smooth bass impact and dynamics, with a rated bass extension down to a flat 20 Hz, that I perceived as being absent from my speakers sound qualities. The system is the Audio Kinesis Swarm system. Here's an Absolute Sound review that provides a very accurate description of what to expect:
https://www.theabsolutesound.com/articles/audiokinesis-swarm-subwoofer-system/ I'm fairly certain this system will perform equally well as a supplement to your speakers and dramatically transform the rhythm, impact and dynamics of your system.
Best wishes,
Tim