“I’ve since sold the Rels”
l agree with your decision. I have said a lot of good things to endorse the brand on this thread which might appear odd. Honesty and not blind biased judgement should not be on here, but yes l actually agree with you….but only in your case.
l use 40 year old Acoustic Energy AE1 speakers on their designed pedestals. I bought some newer Acoustic Energy Reference 1 speakers thinking it was a good choice to upgrade. The two Rel T9i subs l have just would not meld with the new ones…..too much bass and my settings were so low on the subs to almost make them redundant. The problem however was not with the Rels but with the speakers.
The Regerence 1’s bass response is formidable for the size of speakers. They go down to the 40Hz area you talk about. The Rels were just filling in the last 10 Hz of their specification. They were almost off just filling in one octave of range.
I lived with the new speakers for a few weeks and realised there was just no grand spacious and beguiling sound coming forth. I switched back to the old AE 1’s and put the Rels on again…..The magic returned… large soundstage and dynamics.
l came to the conclusion that the newer Reference 1’s didn’t need any subs, they were that good with just the last octave missing. End of story… l am now still using the original 1984 Acoustic Energy AE1 mk1’s and the Rels.
l think your speakers must have had the same roll off and a bit of overhang on the bass response to make the Rels meaningless.
For me it proved the older speakers still hold their own but with bass reinforcement. The newer ones are now in my second system where the extra bass is not required.
Hope this may help explain some other aspect of sub or no sub integrations