T&F are great speaker builders, but I see the RA is indeed listed at 40hz , f-6db. The Isis is 28. Perhaps as Gear says it could be the room setup. The ISIS loaded the good sized mini-conference room at Zurich show and Andreas was not there and asked me what I thought. When I told him, he seemed genuinely disappointed, so it could have been a setup issue indeed. Andreas is a straight shooter who I trust.
Golden ratio.
Golden ratio.