Here is a short review of the T7i. REL's design goals and philosophy, especially with the T series is not for everyone. For example, the T7i is 6db down at a fairly high for a subwoofer 30hz. In practical terms, if you have floor Standers it's very likely that the mains have more frequency extension than the T7i. To call it a sub is a misnomer in this case, because it's not extending frequency response of the mains. Since there is not much output from the sub below 30hz, highly unlikely to activate room nodes or cause booming. The sub is also playing within the frequency range of the mains in my case, so there are no cross over integration issues. With the speaker level inputs, the bass enhancement is so subtle it's really easy to miss what REL is adding to the sound. So, what does it do to the sound? Male voices sound deeper. The sub seems to be restoring a large part of the ambient sound in the recording, as a result the sound stage is much better defined. The system sounds fuller. This sub can elevate mid-fi systems to another level.
REL has prioritised integration, speed and accuracy over extension and high output. Many folks looking for real authority in the stygian depths will be disappointed I suspect. The rewards are in refinement, seamless integration and top quality bass within the confines of the frequency envelope. If you are not into loud then this Sub is for you.
Personally, I would have liked a little more extension and a bit more authority in the mid 20s. Sub is currently placed away from room boundaries, I will experiment a bit by placing the sub in the corner.
On the subs extension, I am somewhat disappointed.
Owners of planar speakers who are worried if the sub will be fast enough can rest their minds, this is the sub to get. This sub is the perfect partner for tiny bookshelf speakers in small to medium spaces. Folks who are invested in tube amplification especially of the SET kind will definitely appreciate this. So yes, there is a reason why it's called an audiophile sub.